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UCL EDUCATION & INFORMATION SUPPORT DIVISIONINFORMATION SYSTEMS

Getting more from Photoshop Elements

Document No. IS-079

ContentsPainting tools....................................................................................................1

Paintbrush 1Other brush tools 2Eyedropper 3

Advanced selections..........................................................................................4Lasso selection tools 4Colour based selections 5Select menu – advanced options 6

Transformations................................................................................................7Free Transform 7Skew / Distort / Perspective 7

Layers................................................................................................................8Layers palette 8The Layer menu 10Text and Shapes 11

Colour correction............................................................................................12The Info palette 12The Enhance menu 12Useful Shortcuts 17

Filters..............................................................................................................18Blur 18Noise 19Sharpen 19

Adjustment Layers...........................................................................................20Creating an Adjustment Layer 20Altering the Layer Mask 20

Appendix 1.......................................................................................................21Photoshop and Photoshop Elements - Differences 21

Learning more.................................................................................................23Getting help with Photoshop Elements 23

IntroductionThis workbook is intended for those who have already completed the Introduction to Photoshop Elements course (or who are already familiar with the Photoshop Elements interface, resizing images and saving for the web) and who want to use it to improve the quality of images – be they digital photographs or scans.

Training filesThis guide can be used as a reference or tutorial document. To assist your learning, a series of practical tasks are available in a separate document. You can download the training files used in this workbook from the IS website at: www.ucl.ac.uk/is/documents

Document No. IS-079 06/07/2006

Manipulator

Painting toolsPhotoshop Elements includes various tools that allow effects to be painted directly onto an image as well as more traditional painting and drawing tools. The most useful, in terms of improving an already existing image’s quality, are detailed here.

PaintbrushThis is a standard paintbrush that applies the foreground colour onto an image, and will be used as an example of the available brush settings. Note that not all these settings are available with all brush types and some brushes have additional settings.

Pop-up paletteClick on the arrow to open a palette of preset brushes. You can then select one of the existing brushes. The palette menu also allows you to manage how the brush previews are displayed; the set of brushes available; and to create, rename and delete brushes from the palette.

Brush optionsClick the brush preview to open the brush options. These allow you to change:Diameter – the size of the brush.Hardness – relates to the edge of the brush – higher settings will make the edge sharper.Spacing – If switched on this will determine the spacing between applications of colour: the higher the setting, the more intermittently colour will be applied.Angle – the angle of the brush will only become apparent if the roundness is set to less than 100%.Roundness – reduce this to create an elliptical brush.Create new pre-set – adds a thumbnail of the current settings to the palette.The angle and roundness can also be set using the manipulator – click and drag the dots to adjust roundness and the arrow to adjust the angle.ModeThis is used to set the mode with which colour is applied – the default of Normal is recommended in the majority of cases. It is beyond the scope of UCL Information Systems 1 Painting tools

Palette menu

Create new preset

this document to give details of each mode – please refer to the Help for details.OpacityThis determines the transparency of the colour being applied – 100% will produce a solid colour. 1% will be virtually transparent and lead to an imperceptible effect.Wet EdgesWhen switched on colour will be applied as with a watercolour brush – the edges of the stroke will be thicker and the centre will be slightly transparent.

Other brush toolsThese brushes do not necessarily apply any colour to the image but may instead alter the values of existing pixels in some way.

EraserThis brush is used to erase pixels from a layer. Except in the case of Background layers (see Layers section – page 12) this will result in a transparent area revealing the layer below. Adjusting the Opacity of the eraser will change the resulting level of transparency, where 100% is fully transparent and 1% is virtually opaque. There are also two alternative erasers:Background EraserIn a similar way to the magnetic lasso tool (see Advanced selections – page 5) this brush can distinguish edges where there is a reasonable level of contrast. It will only erase pixels if they fall within the tolerance level - reducing this setting will increases the sensitivity.Magic EraserThis uses colour values to determine which pixels to erase. Adjust settings just as with the Magic Wand tool (see Advanced Selections) and click on the area you wish to erase. An alternative option is to use the Magic Wand to select an area and then delete it – you can then see the area that is about to be deleted.

Blur / SharpenThese tools blur or sharpen the area the brush stroke is applied to. Increasing pressure in the Options bar will increase the amount of blur or sharpness applied with each stroke. Note that excessive sharpening can highlight compression artefacts in compressed file formats.

SpongeThis allows you to increase or decrease the saturation of the pixels you apply it to – making colours look more vibrant or reducing them towards greyscale. Choose between Saturate – to make colours more vivid - and Desaturate – to remove colour - and set an appropriate pressure.

Appendix 1 2 UCL Information Systems

SmudgeThis smudges the existing pixels in the direction of the brush stroke. The Mode can be used to determine which pixel properties are ‘smudged’. The Finger Painting option will apply the Foreground Color and then smudge it.

Dodge / BurnThese two tools lighten and darken the pixels they are applied to. Use Range to restrict which shades will be affected and Exposure to adjust how much the effect is applied with each stroke.

UCL Information Systems 3 Learning more

Clone StampThis brush uses the image, or another image, as the source for the colour values it applies. This means you can select one part of an image and paint it onto another. This is particularly useful when you need to repair textured areas of an image (e.g. in an old photograph) as it allows you to use existing texture and paint it directly over the damaged portion. 1. Hold the Alt button and click at the point on the image that you wish to use

as the source – this doesn’t have to be the image you’re painting on: simply open the source image alongside the original and select the source point.

2. The brush size and settings can be altered as with other brushes – using a soft edged brush (i.e. with low Hardness setting) will make it easier to blend in with the existing texture. Aligned determines whether the source of each brush stroke remains relative, or starts again, from the point selected in step 1.

EyedropperWhilst this is not actually a brush it deserves mention in this section. It allows you to take an existing colour from an image and set it as the foreground colour. Change the Sample Size as follows:Point Sample – Uses the colour of a single pixel to determine the colour.3 by 3 Average – Uses an average of 3 by 3 pixels to determine the colour.5 by 5 Average – Uses an average of 5 by 5 pixels to determine the colour.


Advanced selectionsWhilst marquee selections have their uses, they are relatively limited: most subjects are not rectangular or elliptical! Photoshop Elements includes several powerful tools for generating complex selections. You should remember that you can refine selections using the add/subtract/intersect selection options – and that you can switch between selection methods whilst doing so.

Lasso selection toolsAs with the geometric selection tools you can access several types of freeform selection tool:Name Advantages Disadvantages

Smoothly curved selections

Fiddly – needs a steady hand!

Easier to use Not as good at creating smoothly curved selections

Combines ease of use with smooth selections

Requires good contrast between background and area to be selected

LassoA freehand selection tool – good for making rough selections, or where speed is more important than accuracy. Requires a steady hand and preferably a graphics tablet.1. Click on your image at a point where you wish to begin your selection and

keep the mouse button held down.2. Move the mouse to ‘draw’ the selection around the desired area, returning

to the point at which you began.3. Release the mouse button to close the selection. If you don’t return to the

starting point a straight line will be used to connect to it.

Polygonal LassoThis works like ‘join the dots’ and makes it easier to create complex selections without the need for a steady hand.1. Click on your image at a point where you wish to begin your selection.

Release the mouse button. This anchors your selection to that point.2. Click and release at the next point along the area to be selected – the

selection will now be anchored to this point.


3. Continue in this way all round the desired area. Use more clicks on those areas with more detail or to create smoother curves. If you misplace an anchor point the Backspace or Delete key can be used to remove it.

4. Either return to the start point or double click to close the selection.


Magnetic LassoThis is a semi-automatic method of creating selections that works well on areas with good contrast.1. Adjust ‘magnetic settings’ – see below.2. Click on your image at a point where you wish to begin your selection.

Release the mouse button.3. ‘Draw’ around the desired area – the selection will automatically ‘anchor’

itself to the edge of the area, so long as it contrasts sufficiently with the background colour. You can manually set an anchor point by clicking the mouse button. You can delete anchor points by pressing the Backspace or Delete key on your keyboard.

4. Return to the start point or double-click to close the selection.

Magnetic settings Width (1 – 40)

The area around the pointer that is used in the procedure. (With the tool selected, but not in use, press Caps Lock on the keyboard to switch the cursor to a visual representation of this area.)

Edge Contrast (1 – 100%)The sensitivity to contrast - lower values make it more sensitive.

Frequency (0 – 100)The frequency at which it sets an anchor point.

Colour based selectionsPrevious selection methods have required the user to manually trace the area to be selected. Photoshop also includes selection methods that work by using the colour values of pixels to automatically create a selection.

Magic WandThis tool creates selections based on the colour values of pixels within the image. It will achieve best results when the area to be selected contains a large area of fairly uniform colour that contrasts well with surrounding colours. To make a selection click on the colour in the image that you want to use as the basis of your selection – for example if you want to select the sky you would click on the blue colour that is most prevalent.Options New/Add/Subtract/Intersect – these are covered in the Introduction to

Photoshop Elements workbook. Tolerance – this controls the sensitivity of the selection process: the lower

the number the more similar a pixel has to be to the initially selected colour for it to become part of the selection. Higher numbers will include more and more pixels in the selection, with 255 as the maximum – equivalent to Select | All.

Anti-aliased – If ticked this will avoid aliasing in curved portions of the selection (recommended).


Contiguous – If ticked the selection process will spread outwards from the point clicked, searching for all adjacent pixels within the tolerance range. When not ticked the selection process will select pixels across the whole image that fall within the set tolerance.

Use all layers – Tick this if the selection should be made across several layers, otherwise it will only use the currently selected layer.


Select menu – advanced optionsFeatherWith some selection tools it’s possible to set the amount of feathering before making a selection. This renders the borders of the selection gradually more and more transparent so the selected area will, for example, blend with the background of any image it is pasted into. The size of the feathering is set in pixels – the amount entered will depend on the pixel size of the image being worked on as well as the amount of blending that is required.The Feather option in the Select menu allows you to apply feathering to an already existing selection. Simply enter the pixel value required. Note that it is not possible to reduce the amount of feathering once it has been applied.

Modify Border – Takes the current selection and creates a feathered selection

bordering it. Set the width of this bordering selection in the dialog box. Smooth – Removes stray pixels from selections (i.e. resulting from using

the Magic Wand). It will also result in a slight loss of sharpness at the edge of selections.

Expand – Enlarges the selection by the number of pixels entered in the dialog box.

Contract – Shrinks the selection by the number of pixels entered in the dialog box.

GrowThis uses the colours of pixels within an existing selection as the basis for a contiguous Magic Wand selection. So it will use all the colours within the current selection and expand the selection outwards finding all adjacent pixels that match these colours, within the tolerance value set.1. Switch to the magic wand and enter the desired tolerance in the Options

toolbar.2. Apply the Grow command from the Select menu.

SimilarUses the colours of pixels within an existing selection as the basis for a non-contiguous Magic Wand selection. So this will take the colours within the current selection and select all instances of these, within the tolerance value set, wherever they appear in the image.1. Switch to the magic wand and enter the desired tolerance in the Options

toolbar.2. Apply the Similar command from the Select menu.


TransformationsThe transform tools (Image | Transform | … ) can be used to make various changes to a layer or selection. When working on a Background Layer they can only be used on a selection.Whichever tool is chosen, a rectangular manipulation box will appear around the selection or layer element. This has various control points which are used to manually apply the desired transformation.The simplest transformation is to change the position of the selected object. To do this click and drag inside the manipulation box. Some changes can also be applied by altering the values in the dialog boxes that appear in the Options bar.Note: Transformations can result in loss of quality – for example enlarging an element will have the same effect as using the resize tool – i.e. lead to a blurring of the enlarged element.

Options barAnchor point – only applies when a rotation is being performed. Defines the point around which the selected object rotates (by default the centre). Click on any point to make that point the centre of rotation.Width and Height – percentage values can be entered to resize the element. Click the chain icon in the middle if you wish to retain the same aspect ratio.Rotation – enter a value between -180 and + 180 degrees.

– Use these buttons to restrict transformations to rotating, resizing and skewing respectively.

– Once a transform tool has been launched you will not be able to continue editing the image, or in fact save it, until you have either accepted or rejected the transformation. Use these buttons to accept or reject the changes. Alternatively double-click on the object or hit Enter to confirm and use Escape to cancel.

Free TransformThis tool allows you to resize and rotate the selected element.Rotate - move the cursor outside of the manipulation box – it will change to a curved, double-headed arrow. Click and drag to rotate.Resize - click on one of the corners and drag the mouse. Hold the Shift button down to retain the same aspect ratio.Stretch - click on either side or the top or bottom control handles and drag to stretch the element in that direction.

Skew / Distort / PerspectiveThese three tools all allow you to distort the shape of the element but restrict changes in specific ways:


Skew – Use the middle handles to apply a slant to the element.Distort – Use the corner handles to distort the element.Perspective – Use the corner handles to give the illusion of perspective, or to correct existing perspective effects (e.g. convergent lines in images of buildings).


LayersLayers are one of the most powerful tools Photoshop has at its disposal. Conceptually they’re fairly simple: Think of them as sheets of glass, each of which can hold image elements. These elements need not take up the entire layer, so any part of a layer with no colour applied will remain transparent, revealing the layers beneath. Layers are mobile so that elements can be re-positioned and the order in which the layers are stacked can also be altered. Editing (e.g. applying colour correction) is also restricted to the currently selected layer.So layers serve several useful functions: They can be used to preserve selections – just copy and paste a selection

and it will be moved to a new layer. Making changes or additions on a new layer allows you to remove those

changes at a later date, and without affecting other layers, simply by deleting the layer.

Separating elements onto layers means that they can be edited or moved individually.

Note: Layers will only be preserved in documents if these are saved in an appropriate format – whilst working with layers it’s best to save the image in the Photoshop format (.psd).

Layers paletteThis palette displays layers and provides tools to manage them, as well as options to add new layers and delete layers.


Active layer

Inactive layer

Blending mode Opacity

Lock LayerLock transparency

Palette menu

Visibility icon

Delete layer

Create new layer

Create new fill or adjustment layer

Link layer

The Background layerIn most cases, unless an image is created from scratch with transparent contents, it will have a Background layer which has special properties: The layer is locked and cannot be unlocked. Its position cannot be changed and it cannot be moved up and down the

layer stack. You cannot change its blending mode or opacity. You cannot make it transparent – deleted or erased areas will be replaced

with the background colour.You can easily convert a background layer into a normal layer to which the above restrictions do not apply: From the Layer Menu select New | Layer from Background.

Managing layersEach layer is represented as a row in the layers palette. This includes a thumbnail of the layer contents, the layer name and additional options.Selecting a layerSimply click on the layer thumbnail for the layer you wish to edit. The selected layer will be highlighted in blue. This will limit changes to this layer, except in special circumstances (see linking layers below), or when a tool option has been set to Use All Layers.Renaming a layerIt’s good practice to give each layer a relevant name so you can easily distinguish between layers. Double-click on the layer in the layer palette, or right-click and select

rename layer. A dialog box will open – change the name and click OK. Moving a layer up and down the layer stackClick on the layer thumbnail, drag it to the desired position in the stack and release the mouse button.Hiding the contents of a layerIt may at times be useful to hide a layer temporarily whilst you work on other layers. Click on the eye icon to hide the layer, it will be replaced by an empty space to denote that it is now hidden. Click on the icon space or reselect the hidden layer to unhide it.Linking layersCertain actions (e.g. moving and transformations) can be carried out on several layers at once. Click in the link layers box to create a link to the currently selected layer – a chain icon will appear. Click again to remove the icon and unlink the layers.


Other optionsBlending modeThis determines how the current layer blends with layers beneath it. The default is normal. It is beyond the scope of this document to give details of each mode – please refer to the Help.OpacityUse this to set the transparency of the layer – 100% is opaque. As the value is decreased – either by clicking on the little arrow to the right and dragging the slider, or entering a value directly - the layer becomes more and more transparent with 0% being totally transparent.LockLocks the layer so it cannot be moved or edited. You can choose to lock only transparent areas (so they will remain transparent when applying colour or effects) or you can lock the entire layer.New Fill/Adjustment layerClick to create a special type of layer – see Adjustment layers – page 27.New layerClick to create a new layer. This will be placed in layer stack directly above the currently selected layer.Delete layerClick to delete the currently selected layer (or drag the layer you wish to delete onto this icon).Palette menuIncludes shortcuts to options in the layer menu and also allows you to change the size of the thumbnails displayed in the layer palette (Palette Options).

The Layer menuThis menu contains additional layer options, some of which duplicate those in the layers palette. The main options are detailed below.

New...Layer – creates a new layer above the currently selected layer.Layer from Background / Background from Layer – converts the Background Layer to a normal layer or the currently selected layer to a Background Layer.Layer via copy – If a selection has been made this will copy the contents of the selection to a new layer. If no selection has been made it will copy the entire selected layer.Layer via cut – Only available when a selection has been made. Cuts the selection from the current layer and pastes it into a new layer.

Duplicate LayerCreates a copy of the current layer (can also be accessed with right-click menu). In the dialog box give the new layer a name. You can also choose to create the copy in a new image.Appendix 1 14 UCL Information Systems

Delete/Rename LayerDelete/Rename the currently selected layer.

New Fill/Adjustment LayerFor details of these see later section.

Simplify LayerRenders a vector based layer (e.g. text or custom shapes) to a raster format. See the section on Text and Custom Shapes below for further information.

ArrangeThis sub-menu gives options to move the currently selected layer up and down the layer stack

Merge Linked/VisibleThis will combine all linked or visible layers into a single layer. This is only recommended if you no longer need to make separate changes to each of these individual layers.

Flatten ImageThis will combine all layers into a single layer. This is not recommended! If you need a flattened version of the image make a backup of the PSD file first. When saving in formats that do not support layers the image will automatically be flattened.

Text and ShapesWhilst there isn’t time to go into the details of creating Text or Shapes; it is appropriate to document how they behave vis a vis layers.When added to a document both text and shapes are created as vector objects on a new layer. Vector objects can be scaled and transformed without loss of detail and text can be edited in various ways. As well as being able to add or edit it directly, as you would in a text editor, you can also format it: changing font, colour and size etc.However, vector objects do have certain limitations: they cannot share the same layer with a raster1 object and raster based effects cannot be applied to them – so, for example, it is not possible to paint on a text or custom shape layer using the brush tool.If you need to apply a raster effect to a vector layer it will first need to be converted to a raster format: Layer | Simplify Layer. This reduces the text or shape to a raster, which means that it can now only be edited with raster tools - so text can no longer be formatted or edited directly and scaling and transformations will potentially result in a loss of detail.

Note: To preserve vector objects within the document when saving, ensure it is saved in PSD or other appropriate format.

1 Vector objects are stored mathematically whereas raster objects are made up of pixels.UCL Information Systems 15 Learning more

Colour correctionThe Info paletteWhen using colour correction tools it is often useful to know the colour values of pixels within an image. The Info palette will, by default, display the Actual Colour (as an RGB value) of the pixel under the cursor. It also displays the position of the cursor, the size of a selection and also context sensitive

information, which can also be used to display colour values in an alternate format.

Click on the eyedropper icons to change the colour format displayed. Click on the to change the scale used for the cursor position. The context sensitive information will change depending on which tool is currently selected.

The Enhance menuAuto LevelsApplies the Levels command (see Brightness/Contrast below) and makes adjustments automatically based on existing pixel values. This can lead to unwanted changes in colour balance and is not recommended.

Auto ContrastAutomatically adjusts the brightness and contrast of the image, making adjustments based on existing pixel values.

Adjust BacklightingAdjust the slider to compensate for over-exposure – Photoshop will attempt to automatically identify overexposed areas and reduce their brightness.

Fill FlashAdjust the slider to compensate for under-exposure – Photoshop will attempt to automatically identify under-exposed areas and brighten them.

ColorColor CastDifferent lighting conditions can affect the way a camera captures colour, making the picture look as though it has been tinted. For example fluorescent lighting often gives images a yellow or green tint. This tool is used to correct


Actual Colour (default)

Cursor position

Context sensitive information

Selection size

these ‘colour casts’, but also has the potential to create them so should be used with care.


1. Click on a colour in the image that you know should be black, white or a neutral grey.Any of these three colours should contain an equal amount of red, green and blue, so Photoshop will use the selected pixel to determine which colour is causing the cast and adjust all pixels appropriately.

2. If necessary click on another pixel to apply a subsequent colour adjustment. You also have the choice to click on Reset to reset the colours to their initial state and start from scratch.

3. Click OK when you are happy with your adjustments.Helpful hint: You can often tell what colour the colour cast is by eye alone and pick a pixel that will compensate appropriately by checking the Info palette – for example if you know there’s too much blue in the image, find a pixel that has matching values for red and green and a larger amount of blue. Clicking on this pixel will make Photoshop reduce the blue values in all pixels.

Hue/SaturationThis can be used to adjust colour values across the entire image (choose Master from the drop down) or can be restricted to a range of colours. The two colour bars at the bottom of the dialog box represent the original colour and the output colour after changes have been made to the Hue. They are

also used to display the range of selected colours.

1. Choose Master or a colour range from the drop down box.2. If necessary adjust the range:

Use the eyedropper tools to select a new colour, or to add or remove colours from the range. Note that you can only select a contiguous range of colours. So, if you initially selected Reds and added green the affected colour range would also include yellows.

Move the sliders to select the colour range and drop-off (colours within the drop-off will be partially affected by any changes made).

3. Make adjustments to Hue, Saturation and Lightness as required.4. Click OK.HueMoves all existing colour values, or those within the selected colour range, around the colour wheel. Look at the colour bars at the bottom to see the effect.


Colour range

Original colourAdjusted colour

Select new colour

Add to colour range

Subtract from colour range

Adjust drop-off Adjust colour range

SaturationAdjusts the strength of the colour – decreasing saturation will reduce colour intensity whilst increasing it will make colours appear stronger and more vibrant.LightnessUsed to adjust the shade of the colour values.ColorizeThis is designed to tint greyscale images with colour. Ensure the image is in RGB mode (Image | Mode | RGB Color).

Remove ColorReplaces all colour in an image with an appropriate shade of grey, but does not change the image mode. If the image is to remain in greyscale you can reduce file size by switching the image mode to Grayscale (Image | Mode | Grayscale).

Replace ColorThis tool achieves similar results to the Hue/Saturation tool but uses a colour-based mask to select the pixels to effect. The main advantage of this is that, unlike the Hue/Saturation tool, you can adjust non-contiguous groups of colours. So you could select all red and green sections of an image and adjust

these without affecting any yellow sections.

1. Use the eyedropper tools to select, add or subtract colours from the mask – you can click either on the image directly in the work area, or by selecting Image in the dialog box and clicking on the thumbnail.

2. Set the Fuzziness to adjust the tolerance of the selection – the higher the number, the more pixels will be included in the selection (this is similar to


Switch between selection preview and image thumbnail

Selection tolerance

New mask

Add to mask

Subtract from mask

the tolerance setting on the Magic Wand tool). Click on Selection in the dialog box to see a visual representation of the selection.

3. Make adjustments to Hue, Saturation and Lightness as required.4. Click OK.


Brightness/ContrastBrightness/ContrastThis option is useful for minor changes to brightness and contrast, though the Levels tool is recommended if you need more control over the effect.1. Use the sliders to adjust brightness and contrast.2. Click OK.

LevelsLevels are without doubt the best option available when adjusting the tonal range of an image. They allow you to alter the values of shadows, midtones and highlights independently of each other, rather than adjusting across the board as happens with the Brightness/Contrast tool. They are also the more complicated option, not least as it’s possible to use different methods to

achieve the same result and it’s also possible to apply changes to individual colour channels.

The HistogramThe histogram in the middle of the dialog box represents the distribution of colour shades across the entire image, current layer or selection. In most photographs that don’t contain large amounts of white or black the ideal histogram will be a bell curve, not dissimilar to the one in the screenshot above. If the curve is centred towards the left then the image/selected area is likely to be under-exposed (too dark). If it is towards the right then it has probably been over-exposed (too bright).Input LevelsThe input levels can be adjusted to make shadows darker; highlights lighter and make midtones either darker or lighter. To darken shadows increase the value in the first Input Levels box, either

by entering a figure directly, or by dragging the black slider to the right. To lighten highlights decrease the value in the third Input Levels box,

either by entering a figure directly, or by dragging the white slider to the left.


Histogram

Input level sliders

Output level sliders

To adjust midtones change the value in the second Input Levels box, either by entering a figure directly or by dragging the grey slider to the left or right.

Generally speaking the shadow and highlight values should correspond to the beginning and end of the curve, but can be pushed beyond this as required. Excessive adjustments can lead to loss of detail or clipping (for an explanation of this see Variations – page 24) as well as unrealistic results.


Output LevelsThese can be used to reduce the amount of contrast in an image or avoid unrealistic levels of black and white. Generally speaking areas are unlikely to appear totally black or white in real life. Increasing the shadows or highlights however, can create areas of pure black or white. To lighten shadows increase the value in the first Output Levels box, either

by entering a figure directly or by dragging the black slider to the right. To darken highlights decrease the value in the second Output Levels box,

either by entering a figure directly or by dragging the white slider to the left.

Channel – fixing colour casts with LevelsThe default setting for Channel is RGB. Each pixel in an image has a value set for Red (R), Green (G) and Blue (B) – the RGB setting adjusts the values of all three together, which gives control over the shade of colours in the image.By switching the Channel to one of the three colour channels (Red, Green or Blue) the histogram changes to display the output for that individual colour channel – i.e. the amount (not shade) of that colour in the image. With an individual colour channel specified in this way adjustments in the Levels dialog box no longer effect the shade of colours but instead alter the amount of that colour present in each pixel of the image (or selection). This gives a certain amount of control over colour tints within the image and allows manual correction of colour casts.In order to make effective use of this functionality you need to know that each colour channel has an opposite colour associated with it – by decreasing the value of one of the channels you automatically increase the values for the ‘opposite’ colour and vice-versa. So, for example, if you reduce the Red output you also increase the output of Cyan (see chart below). So to fix a colour cast you need to identify the colour of the cast (the info panel can be useful here), switch to the appropriate colour channel and make adjustments as necessary.

Channel OppositeRed CyanGreen

Magenta

Blue Yellow

Note: The full version of Photoshop includes a very powerful colour correction tool called Channels.


VariationsThis is a visual tool for changing colour, contrast and saturation in an image.1. Chose what you wish to affect with your alterations:

Shadows, Midtones or Highlights: Changes will affect the colours that fall within the specified range of shades.

Saturation.1. Select the intensity of the effect using the Fine / Coarse slider.2. Click on the thumbnail that matches your requirements – the Current Pick

thumbnail will be updated to reflect your changes.3. When you’re happy with all your adjustments click OK.Show ClippingChanges in saturation, colour values and contrast can potentially lead to a loss of detail in the image (where separate colours merge into one), particularly in the Shadows and Highlights – this is known as clipping. Ticking the Show Clipping box will display a visual representation (neon highlights) on the

thumbnails of those areas where clipping will occur.

Useful ShortcutsWhen using colour correction tools it is often useful to be able to navigate an image whilst a dialog box is open, particularly if the chosen tool relies on the selection of colours within the image. In this instance the following keyboard shortcuts are especially useful:

Hand Tool: Space Bar Zoom in: Space Bar + Ctrl Zoom out: Space Bar + Ctrl + Alt


Original and preview

Adjust colour or saturation Adjust lightness

Area to be effected

Adjust strength of effect

FiltersTo apply a filter simply chose the required filter from the Filter menu. Some filters will require you to make adjustments in a dialog box, whilst others will be applied immediately.There are a huge range of filters available for Photoshop and other graphics packages – many are included in the default installation of Photoshop Elements and more can be bought, downloaded and installed as required. As there are so many it is not practical to go through all of them in detail so the most useful, in terms of improving image quality, are detailed below.

BlurBlur / Blur MoreThese filters require no user input. They apply blur across the entire image by averaging adjacent pixel values. On large images the blurred image may look indistinguishable from the original, especially when using just Blur.

Gaussian BlurThis blur method is more useful than the previous two, especially on larger images, as it gives more control over the amount of blurring.1. Set the Radius – the larger the number the more blur will be applied.2. Click OK.

Smart BlurThis filter gives even more control than gaussian blur: it allows you to apply the blur selectively based on levels of contrast within the image.1. Set the Radius – This is the area used to determine the effect. Generally,

images with larger pixel sizes will require a larger radius; small images (e.g. those resized for screen use) are not likely to need a radius setting greater than 1 or 2.

2. Set the Threshold. The higher the value the greater the contrast required on an edge for it to remain unaffected by the blur.

3. Set the quality setting to Low, Medium or High. High may take longer but will produce better results.

4. The Mode options can be used to give visual feedback on which edges will remain sharp and which areas will be blurred:Normal: no visual feedback – switch to this to apply the effect when finished making adjustments.Edge Only: areas in black will have the blur applied – white edges will remain sharp.Overlay Edge: overlays white lines on those edges that will remain sharp.

5. Click OK.


NoiseThe Noise filters can be used to add noise to an image as well as to remove noise artefacts.

Add NoiseThis can be used to add noise (graininess) to an image. This can be surprisingly useful, for example as a means of removing banding in gradient fills.

DespeckleThis removes specks and grain from an image. Depending on the size of the image Dust & Scratches or Smart Blur may be more effective.

Dust & ScratchesThis is similar to the Despeckle filter but gives more fine grain control over how it is applied.

MedianThis reduces noise based on the brightness of pixels.

SharpenSharpen / Sharpen MoreThese sharpen an image to a lesser or greater extent. As with the Blur and Blur More tools they may not have a very strong effect on large images.

Sharpen EdgesSharpens only those areas of high contrast within the image – useful in increasing definition without highlighting artefacts or grain within flat areas of an image.

Unsharp MaskThis is the Sharpening equivalent of the Smart Blur – it gives you far more control over how much sharpening is applied. It’s best to make subtle changes to the settings in this tool as otherwise it can result in very unrealistic results.1. Set the Amount. Higher values will increase the amount of sharpening.2. Set the Radius. As with the blur tool this is the area used to determine the

effect.3. Set the Threshold. Higher values will limit sharpening to those areas with

higher contrast.4. Click OK.

Note: The Sharpen tools are not suitable for use on low quality JPEGs as they will accentuate the pattern used to compress the image.


Adjustment LayersAdjustment layers allow you to apply certain adjustments on a separate layer, thereby preserving the integrity of the original image. They are also combined with a mask, which allows you to paint out those areas where you don’t want the effect applied – this offers many advantages over using selections.

Creating an Adjustment Layer1. Select the layer you wish to apply the adjustments to (the adjustment will

be applied to all layers beneath it).2. Either click on the Create new fill or adjustment layer button on the

layer palette or use the menu: Layer | New Adjustment Layer | ...3. Select the type of adjustment you wish to apply4. If you use the menu to create the adjustment layer you will be prompted for

a layer name etc.5. A dialog box will appear depending on the type of adjustment selected. Set

options as necessary and click OKYou will see a new layer in the layer palette with two thumbnails. On the left is the Layer thumbnail – this is an icon that represents the adjustment applied – on the right is the Layer mask thumbnail – this shows the mask that determines where the effect is applied. You can make further adjustments to the effect by double clicking on the Layer thumbnail: this will open the appropriate dialog box for it.

Altering the Layer MaskThe layer mask is a greyscale image that is used to determine the opacity of the adjustment layer. Pure white indicates full opacity whilst absolute black indicates total transparency. The levels of grey in between represent different levels of transparency, gradually becoming more opaque as they become lighter.This allows you to apply or remove the adjustment selectively by using the Brush tool to change the transparency of the Adjustment Layer.Initially the layer mask is pure white so the adjustment is applied to the whole image. Optionally, use Image | Adjustments | Invert to make it entirely black so that it has no effect. You can then use the Brush tool as follows: Use black to create transparent areas on the adjustment layer. Use white to create solid areas on the adjustment layer. Use shades of grey or different levels of opacity to achieve semi-

transparent areas of the adjustment layer. If you try using a colour with the brush rather than greyscale, Photoshop

will use an equivalent shade of grey.


You can also apply Filters to the mask – e.g. use Gaussian Blur to blend in the edges of the mask.


Appendix 1Photoshop and Photoshop Elements - DifferencesThis workbook is based on Photoshop Elements 1 (this is the version available on WTS). The full version of Photoshop has more tools than Photoshop Elements and also includes additional options for some of the tools available to users of both versions. Despite this, everything covered in this workbook should work in the same way in Photoshop. Most differences will involve additional options or slight changes in menu locations. Changes relevant to the topics covered in this workbook are detailed below.

SelectionsThe selection tools work in exactly the same way in the full version of Photoshop, however you will find a couple of additional options – most notably the Transform Selection option in the Selection menu which allows you to edit a selection using the transformation tools.

TransformationsIn Photoshop all of the options available under Photoshop Elements’ Image | Transform menu are under Edit | Transform, except for Free Transform which is available directly under the Edit menu.

LayersLayer PaletteExtra options on the layer palette include: Lock image pixels and lock position, as well as locking of the entire

layer and transparency as available in Elements. Add a layer mask: a means of hiding or showing elements of the layer

using a greyscale mask. This is an extremely powerful and useful tool with some similar applications as selections and more besides.

Options to manage layers into sets. Essentially this allows you to organise layers into folders.

Layer MenuAgain the Layer menu includes additional options, many of which are related to the additional options in the Layer Palette. Simplify Layer – this option is replaced by several options under the

Rasterize sub-menu.


Colour CorrectionThe full version of Photoshop includes much more powerful tools for colour correction – notably the (rather complex) Curves tool – but fails to include certain automatic tools available in Elements. Given that Photoshop is aimed at professionals, they’ve clearly removed those functions that professionals would never leave to a machine. There are also changes to menu positions of the following: Auto Levels, Auto Contrast, Hue/Saturation, Replace Colour,

Brightness/Contrast, Levels, Variations – These can all be found under the Image | Adjust submenu.

Adjust Backlighting, Fill Flash – neither of these is available in Photoshop. Using Levels is the preferred option to fix those problems that would require these tools (in Elements as well!).

Cast – this automatic tool is not available in Photoshop. Use Image | Adjust | Color Balance or Curves to manually fix colour casts.

Remove Colour – Use Image | Adjust | Desaturate


Learning moreCentral IT TrainingInformation Systems run courses for UCL staff, and publish documents for staff and students. Photoshop/Graphics related documents include:

Introduction to Photoshop Elements

This course is for new users and is geared towards preparing images for use on screen – e.g. web, Powerpoint etc.

Getting more from Photoshop Elements

This 3.5hr course tackles more advanced features such as layers, as well as a range of tools to improve image quality.

Using images in documents

Additional booklet with information on how to achieve good print results from images inserted into documents.

Open Learning Centre Graphics Workshop – This training is delivered in the Open Learning Centre and is intended for those who wish to obtain training on specific features in Photoshop Elements on a individual or small group basis. Please let us know your previous levels of experience, and what areas you would like to cover, when arranging to attend.

You will need to book a session in advance at: www.ucl.ac.uk/is/olc/bookspecial.htm and sessions will last for an hour or possibly longer depending on availability.

See the OLC web pages for more details at www.ucl.ac.uk/is/olc.On-line learningThere is also a comprehensive range of online training available via TheLearningZone at www.ucl.ac.uk/elearning.

Getting help with Photoshop Elements Photoshop Elements has a help system which you can call upon at any time while you are working on a Website. Under WTS this must be opened from the Start Menu using the shortcut in the Photoshop folder. A Web search using a search engine such as Google (www.google.co.uk) can also retrieve helpful Web pages. For example, a search for photoshop selection tutorial would return a useful range of tutorials.


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