preparing images with photoshop resources/how-to guide... · this guide accompanies the preparing...

Preparing

Images with

Photoshop

How-To Guide

Preparing Images with Photoshop – How-To Guide

© 2018 Cardiff Metropolitan University 2

This guide accompanies the Preparing Images with Photoshop training courses. It covers the main

points of the sessions in a step-by-step “How To” manner. You can use this guide as an aid when

completing workbook tasks during the session, or for reference after you have completed the training.

All resources used in the training session, including this guide, are available on the IT Training website:

http://study.cardiffmet.ac.uk/Help/Training/

A Note on Conventions:

Menus and menu options appear in bold italics.

E.g. Image Auto Tone means choose the Image menu then the Auto Tone option.

Photoshop features and tools appear in bold.

E.g. “Use the Free Transform tool to resize or rotate a selection”.

Hints, tips or asides appear within a box. E.g.

TIP: Hints, tips and asides will appear in boxes like this!

Contents

Photoshop Workspace ............................................................................................................................ 4

Tools Panel .......................................................................................................................................... 6

Image Size ............................................................................................................................................... 7

Cropping .............................................................................................................................................. 7

Straightening an Image ................................................................................................................... 8

Resizing an Image ................................................................................................................................ 8

Canvas Size .......................................................................................................................................... 9

Retouching ............................................................................................................................................ 10

Healing Tools ..................................................................................................................................... 10

Spot Healing Brush Tool ................................................................................................................ 10

Content-Aware Fill ........................................................................................................................ 11

Patch ............................................................................................................................................. 11

Adjustments ...................................................................................................................................... 12

Brightness and Contrast ................................................................................................................ 12

Automatic Adjustments ................................................................................................................ 13

Saving and Exporting Images ................................................................................................................ 13

File Formats ....................................................................................................................................... 13

Exporting ........................................................................................................................................... 14

Using Images in Office ....................................................................................................................... 14

http://study.cardiffmet.ac.uk/Help/Training/



Printing Images ..................................................................................................................................... 15

Layers .................................................................................................................................................... 16

New Layer ......................................................................................................................................... 17

Working with Layers ......................................................................................................................... 18

Stacking Order ............................................................................................................................... 18

Background Layer .......................................................................................................................... 18

Duplicating Layers ......................................................................................................................... 18

Opacity .......................................................................................................................................... 19

Transforming Layers ...................................................................................................................... 19

Type Tool ........................................................................................................................................... 20

Organising Layers .............................................................................................................................. 20

Grouping Layers ............................................................................................................................ 20

Working with Groups .................................................................................................................... 21

Aligning Layers .............................................................................................................................. 21

Distributing Layers ........................................................................................................................ 21

Layer Styles ....................................................................................................................................... 22

Selection Tools ...................................................................................................................................... 23

Magic Wand ...................................................................................................................................... 23

Quick Selection Tool.......................................................................................................................... 24

Selection Modes ................................................................................................................................ 25

Deselecting, Reselecting and Inversing the Selection ....................................................................... 25

Masks .................................................................................................................................................... 26

Adding a Mask ................................................................................................................................... 26

Working with Masks ......................................................................................................................... 27

Using Masks with Selections ............................................................................................................. 28

Select and Mask (Refine Edge) .......................................................................................................... 28

Adjustment Layers ................................................................................................................................ 31

Adding an Adjustment Layer ............................................................................................................. 31

Working with Adjustment Layers...................................................................................................... 32

Clipping Adjustment Layers .......................................................................................................... 32

Photo Filter ....................................................................................................................................... 33

Hue/Saturation ................................................................................................................................. 34

Levels................................................................................................................................................. 35



Photoshop Workspace

Images can be edited and manipulated using various tools, panels and windows. In Photoshop, the

arrangement of these elements is called a workspace. The image on the next page gives an

overview of the default Photoshop workspace, Essentials. The workspace includes:

Tools panel – contains tools for editing images. Similar tools are grouped together and can

be accessed by clicking and holding the mouse button on the tool name. Most tools also

have a shortcut key assigned, in this guide the shortcut key will appear in brackets after the

name of the tool. For example, the shortcut key for the Move Tool is V, so it will appear in

this guide as Move Tool (V).

Options bar – sets options for the currently selected tool. For example, with the Brush Tool

(B) selected you are able to change the brush size, flow and opacity through the options bar.

Menu bar – includes commands for using Photoshop features.

Panels – panels help you monitor and modify your images. Panels can be popped out (such

as the History panel in the screenshot), or docked (like the Layers panel).

The Window menu can be used to configure the workspace. You can, for example, hide or show

Panels by selecting them from the menu. Or use the Workspace Reset Essentials option to reset

the workspace to its original configuration.

Click on a panel name to

display/hide it

Tools panel

Options bar

panel

A Panel

A Docked

Panel

Menu bar



Tools Panel

The graphic below shows where the tools we use in the courses are located in the Tools panel.

Move Tool (V)

panel Marquee Tools (M). Selection

tools, includes Rectangular,

Elliptical Lasso Tools (L). Selection

tools, includes Lasso,

Polygonal, Magnetic Lasso Quick Tools (W). Selection

tools; Magic Wand and Quick

Selection Tool Crop Tool (C)

panel

Healing Tools (J). Includes

Spot Healing Brush, Healing

Brush and Patch

Brush Tool (B)

panel

Fill Tools (G). Includes Paint

Bucket and Gradient Tool

Type Tool (T)

panel

Shape Tools (U). Includes

Rectangle, Ellipse, Polygon

Zoom Tool (Z)

panel

Set Foreground and

Background colours



Image Size

The size of an image can be altered by either cutting off pieces that we are not interested in

(cropping), or by altering its dimensions, which may be the on-screen size (measured in pixels) or

printed size (measured in centimetres).

Cropping

To crop an image:

1. Choose the Crop Tool (C) from the Tools panel.

2. Then either:

a. Drag the grab handles at the corner of the crop window so that the area you wish to

keep is within the crop window (the lighter area). The darker area will be cropped

away.

b. Click and drag to draw a box over the area you wish to keep (again, indicated by a

lighter colour).

3. Press the Enter key (or use the Tick icon on the options bar) to commit your changes.

Crop tool settings can be set on the options bar, including:

Cropping in a specific aspect ratio.

Permanently deleting pixels when cropped.

Click and drag

grab handles



Straightening an Image

To straighten an image:

1. Select the Crop Tool (C) from

the Tools panel.

2. Click the Straighten button

on the options bar.

3. Draw a line at the angle that

you wish to straighten.

Resizing an Image

To resize an image:

1. Image Image Size…

2. Choose a new size using the Image Size dialogue:

TIP: Resampling an image will add or remove pixels to an image. It allows an image to be resized

when displayed on a screen. Disabling resampling will change the physical size of the image when

printed, but will not change the size when displayed on screen.

Straightening an image using the Crop Tool

Specify height/width

Lock aspect ratio

Choose dimensions

(e.g. pixels or cm)

Resample or Resize?



Canvas Size

The size of the canvas can be expanded by using the Canvas Size option in the Image menu. This will

not resize or resample the image, but can instead be used to increase the amount of canvas space

available to work with.

To change the canvas size:

1. Image Canvas Size…

2. Use the dialogue to set a new canvas size:

The anchor determines where the canvas will be expanded. By default, the anchor is set to the

middle of the canvas, so any changes to height or width will be applied evenly to the top/bottom

and left/right.

As an example, let’s say we change the width of the canvas above from 25.4cm to 29.4 cm, a 4cm

increase. If we don’t change the anchor, 2cm will be added to both the left and right of the canvas.

If we move the anchor point to the right of the canvas (by clicking the arrow) then the entire 4cm

will be added to the left of the canvas.

Specify new height/width

of the canvas

Change the anchor point

for the expansion

A right anchor point adds space to the left of the canvas



Retouching

Retouching techniques can be used to make quick edits to enhance the appearance of an image. We

will look at two retouching techniques: using healing tools and making image adjustments.

Healing Tools

Healing tools can be used to remove undesirable parts of an image, for example, unwanted objects,

blemishes or artefacts (or defects) from when the photograph was taken. The two most powerful

Healing Tools are the Spot Healing Brush Tool and the Content Aware Fill option. Both of these

tools use Photoshop’s Content-Aware functionality, which works by looking around the area that is

selected (a process known as sampling) and intelligently replacing the content to match the

surroundings.

Spot Healing Brush Tool

To remove content from an image using the Spot Healing Brush Tool:

1. Choose the Spot Healing Brush Tool (J) from the Tools panel.

2. Set an appropriate brush size and ensure the type is set to Content-Aware on the options

bar.

3. Click on, or brush over, the area you wish to remove.

Set options

Brush over the area

you wish to remove



Content-Aware Fill

To remove objects with Content-Aware Fill:

1. Select the area of the image you wish to remove with a selection tool (e.g. the Rectangular

Marquee Tool (M)). Include a bit of the surrounding area so that Photoshop can better

judge the content that needs to be removed.

2. Edit Fill (Shift+F5).

3. On the Fill dialogue, ensure Content-Aware is selected, then click OK.

Patch

The Patch Tool (J) allows content from elsewhere in the image to be intelligently blended with the

selected area.

1. Select the area you wish to patch with a selection tool of your choice (e.g. Lasso Tool (L)).

2. Choose the Patch Tool (J) from the Tools panel.

3. Use the options bar to specify settings for the Patch Tool; ensure Content-Aware is mode

selected. The Structure value (1-7) indicates how closely the patch reflects existing image

patterns. A value of 7 indicates a very strong representation; 1 is very loose. The Color

value (1-10) is used to specify the level of colour blending applied.

4. Click within the selection then drag to the area of the image you wish to use as the patch

and release the mouse button.



5. The patch area will be intelligently blended with the original selection.

Adjustments

Image adjustments can be used to enhance an image’s appearance, for example the brightness and

contrast can be changed to lighten dark images, or increase the contrast to give the image more

impact. Image adjustments are applied to the current selection, or if no selection has been made

the entire layer will be adjusted.

Brightness and Contrast

To adjust the brightness and/or contrast:

1. Image Adjustments

Brightness/Contrast…

2. Move the sliders to increase or decrease the

brightness and contrast.

TIP: Click the Auto button to have Photoshop adjust the Brightness/Contrast for you

Click within the

original selection Drag to the area you wish to

use as a patch then release

the mouse button



Automatic Adjustments

Automatic image adjustments can be made via the Image menu. For example, to automatically

correct the colour and contrast in the image choose Image Auto Color. There are three

automatic adjustments available:

Auto Contrast – darkens the darkest pixels to pure black and lightens the lightest to pure

white, then redistributes the tonal values in between. Auto Contrast does not change the

colours in the image and is therefore best to correct images with contrast issues, but no

colour problems.

Auto Tone – rebalances the tonal range for the individual red, green and blue channels. This

does not affect the overall contrast of the image, but will change the colours in your image

so it should be used to correct images that have an unwanted colour cast (or tint).

Auto Color – works similarly to Auto Tone, but also neutralises the midtones in the image.

This makes Auto Color the best choice for correcting images with colour and contrast

problems.

Saving and Exporting Images

In general, you should save at least two copies of an image. One is the “working” copy that is saved

in Photoshop (PSD) format. PSD format retains essential information that is needed when editing

the image, such as layers and masks.

The second copy should be saved, or more accurately, exported, in a format that is suitable for use

on the web; JPG or PNG. Both PNG and JPG files compress the image, resulting in a much smaller file

size. PNG uses a lossless compression technique, so that no information (i.e. picture quality) is lost

when exported in this way. This can, however, result in larger file sizes than JPG, which discards

unnecessary information when compressing the image. The table below summarises the file

formats.

File Formats

Format Uses Compression File Size

PSD - Photoshop A “working” copy of image, it includes layer information

None Large

PNG - Portable Network Graphics

Publishing to the web, supports transparency

Lossless Small-medium

JPG – Joint Photographic Experts Group

Publishing to the web, use when very small file sizes are required

Lossy Small



Exporting

To export an image:

1. File Export Export As…

2. Set export options:

3. Click Export.

4. Select a file name and location then click Save.

TIP: To quickly export an image choose File Export Quick Export as PNG. For advanced export

options choose File Export Save for Web (Legacy)

Using Images in Office

To use an image in an Office application, such as Word:

1. Export the image as a PNG (see instructions above).

2. In the Office application use the Insert Pictures menu option to insert the image.

TIP: Copy and Paste should not be used to copy images to Office; when images are copied from

Photoshop to Office the image is inserted as a Photoshop object, which is very large and unwieldy.

Set image and canvas

size (if needed)

Set file format



Printing Images

To print images directly from Photoshop:

1. File Print (Ctrl+P)

2. Set the print options:

3. Click Print when ready.

Choose the printer, number of

copies and adjust printer settings

if needed (e.g. duplex, staples)

Set positioning and scale of the

image. Adjusting scale may

degrade the image.



Layers

Layers can be used to composite several elements into one image. Layers are stacked on top of each

other, with transparent areas of a layer displaying content from the layers below.

In the image above, the book is stored on the background layer, the pen is on the middle layer and

the text is on the top layer. When combined together transparent parts (shown here in blue) of the

middle and top layers allow the content from the background layer to “shine” through. So the image

appears as below:



New Layer

There are a few ways to create a new layer, either: Layer New Layer…, or press Ctrl+Shift+N or

use the new layer button on the Layers panel:

New Layer from Image

To insert an image as a new layer:

1. File Place Embedded…

2. Locate the image on your computer then click Place.

3. The Free Transform tool will be initiated; use it to resize, rotate or move the placed image.

4. When you are happy with the placement of the image, press the Enter key or click the Tick

icon on the options bar.

TIP: An alternative way to place an image is to drag it onto an open image



Working with Layers

The Layers panel allows us to work efficiently with layers; ensure it is displayed by choosing:

Window Layers (F7).

Stacking Order

The order of layers can be adjusted via the Layers panel by dragging and dropping layers into order,

the top layer is displayed at the top of the Layers panel, the bottom layer at the bottom.

Background Layer

When a new image is created, the bottommost layer is called the Background layer, this cannot be

moved, resized or have its stacking order changed. However, it can be converted into a regular layer

by double-clicking on it, or by clicking the padlock icon:

Duplicating Layers

Layers can be duplicated in a couple of ways. To duplicate a layer within the same image: select the

layer from the Layers panel, hold down the Alt key then drag and release.

TIP: It is a good idea to duplicate the original layer before making edits, this allows changes to be

reverted if necessary

To duplicate a layer from one image to another:

1. Open both images.

2. Select the layer you wish to copy in the Layers panel.

3. Layer Duplicate Layer…

4. Choose the other image as the destination in the Duplicate Layer dialogue:



Opacity

The transparency level of an entire layer can be set by the Opacity slider in the Layers panel, from

0% (completely transparent) to 100% (completely opaque).

Transforming Layers

Layers can be resized, rotated and moved with the Free Transform tool. Select the layer you wish to

transform, then Edit Free Transform (Ctrl+T).

To commit your changes press Enter or click the Tick button on the options bar.

TIP: The options bar can also be used to set transformation options. You can, for example, set the

exact degree of rotation via the Angle box.

Click and drag a corner to

resize (hold Shift to main

aspect ratio)

Hover outside a corner

or edge, then click and

drag to rotate

Click and drag to move



Other transformations, such as Skew and Flip are available by choosing a transformation from the

Edit Transform menu.

Type Tool

The Horizontal Type Tool (T) can be used to add text to your images. The text is added as a new

layer, which can be manipulated in the same way as any other layer.

To use the type tool:

1. Choose the Horizontal Type Tool (T) from the Tools panel.

2. Either, click once where you want to add text, then type in your text. Or, draw a box that will

contain your text, then type.

3. To commit your text press Enter or click the Tick button on the options bar.

Use the options bar to set your text options, such as font type, size and colour.

TIP: To edit text after it has been committed, select the layer containing the text then use the

Horizontal Type Tool (T).

Organising Layers

Layers can be organised into groups, which can be useful when working with a large number of

layers. Layers can also be aligned and distributed neatly by using the options bar for the Move tool.

Grouping Layers

To group layers together, click the Create new group button at the bottom of the Layers panel then

drag layers into the new group. Alternatively, select the layers you wish to group first, then click the

button:



Working with Groups

When layers are arranged into groups, any actions you perform on the group will apply to all the

layers within it. Examples:

Using the Move Tool (V) will move all layers in the group together.

Free Transform (Ctrl+T) can be used to resize grouped layers.

Layer Styles can be applied to a group to, for example, add a shadow to each layer.

It is a good idea to rename your groups, especially if there are many layers in the image. To do so,

double-click on the group name and type in a new name.

Aligning Layers

Layers can be aligned neatly using the Move Tool’s (V) alignment buttons on the options bar.

To align layers, select the layers (at least two) you wish to align from the Layers panel. Choose the

Move Tool (V) from the Tools panel then select an alignment option:

The first three options Align top edges, Align vertical centres and Align bottom edges align the

selected layers vertically. The next three Align left edge, Align horizontal centres and Align right

edges align layers horizontally.

Distributing Layers

The layer distribution options can be used to evenly space layers. To use them choose the Move

Tool (V), select at least three layers then choose a distribution option:

The first three options distribute layers evenly on the vertical plane. The difference between the

options is the starting point for the distribution. For example, the first option spaces the layers

evenly starting from the top pixel of each layer.



The second three options distribute layers evenly on the horizontal plane. Again, the different

options represent different starting points.

Layer Styles

Layer Styles can be applied to a layer to add effects, such as Drop Shadows or Gradients, to a layer.

To apply a layer style:

1. Select the layer using the Layers panel.

2. Layer Layer Style then choose a layer style from the menu.

3. Use the Layer Style dialogue to set options for your layer style(s).

The style options vary depending on the Layer Style that you have selected. Some common settings

include:

Angle – the angle of the light source that casts a shadow effect.

Blend mode – how the layer style interacts with other layers.

Distance – the distance of a shadow or satin effect from the source layer.

Gradient – set the gradient pattern (double click to edit).

Size – the size of a shadow, or size and radius of a blur effect (such as Outer Glow).

Spread – extends the size of the matte part of a shadow (use in conjunction with Size).

Enable a style

Click to adjust style options

Set style options



Selection Tools

Selection tools can be used to select parts of an image. The selection can then be copied to a new

layer (or new image) so that it can be edited separately from the rest of the image.

Photoshop has a range of selection tools available. The simplest tools – the Rectangular and

Elliptical Marquee Tools (M) – can be used by clicking and dragging to draw shapes. The Lasso Tools

(L) can be used to draw selections in a more freeform manner, however by far the most powerful

tools are the Magic Wand (W) and Quick Selection Tool (W).

Magic Wand

The Magic Wand (W) selects areas of an image that are of a similar colour. To select using the Magic

Wand.

1. Choose the Magic Wand (W) from the Tools panel.

2. Set your options on the options bar:

3. Click on a colour in your image to select.

The Tolerance (0-255) is the

range of colours selected. The

higher the tolerance, the more

colours selected.

If Contiguous is enabled, only

colours that are next to each

other (and in the tolerance

range) will be selected.

Choose selection

mode, e.g. New or

Add (see page 24)

A tolerance of 36 with

contiguous enabled, selects the

darker parts of sky, but not the

lighter parts or the sea.



Quick Selection Tool

The Quick Selection Tool (W) can be used to select parts of an image by “brushing” over them.

Photoshop uses a clever algorithm to detect differences in colour and texture making selection quick

and easy.

To use the Quick Selection Tool:

1. Choose the Quick Selection Tool (W) from the Tools panel.

2. Set the selection mode (see below) and brush size on the options bar.

TIP: Start with a large brush size, then reduce the size (shortcut: [ ) to make finer selections.

Make use of Subtract from selection (hold down Alt) if you select more than you intend.

3. Brush with the Quick Selection Tool to select areas of the image:



Selection Modes

Areas can be added to a selection, or removed (subtracted) by changing the selection mode on the

options bar:

Working from left-to-right, the icons are:

New selection – discard any existing selections and start afresh.

Add to selection – add to your existing selection.

Subtract from selection – remove parts from your existing selection.

Intersect with selection – the area of overlap between your new selection and existing

selection becomes the selected area.

Selections can be added to, or subtracted from, with any selection tool. For example, you may begin

a selection with the Elliptical Marquee Tool, then add finer detail with the Quick Selection Tool

(note, the selection mode icons for the Quick Selection Tool are slightly different, but the principal is

the same).

TIP: to quickly (and temporarily) switch to add mode, hold down Shift. To subtract, use Alt.

Deselecting, Reselecting and Inversing the Selection

To deselect an area: Select Deselect (Ctrl+D).

To reselect an area (after deselecting): Select Reselect (Shift+Ctrl+D).

To inverse the selection (i.e. make everything that was selected, deselected and everything that was

not selected, selected): Select Inverse (Shift+Ctrl+I)

TIP: To quickly select all visible pixels on a layer, hold down Ctrl and click on the layer thumbnail in

the Layers panel.



Masks

Masks can be added to a layer to show or hide parts of that layer. They can be used to blend layers

together and to refine selections.

Masks primarily use two colours, black and white, to hide or show content:

White areas of the mask are visible

Black areas of the mask are hidden

Black areas are actually transparent; they show content from the layers below. In fact masks use a

greyscale to control transparency, not just black and white. The level of grey corresponds to the

transparency level; dark grey areas are quite opaque, light grey areas are very translucent.

Adding a Mask

To add a mask use the Add layer mask button at the bottom of the Layers panel:

The mask then appears alongside the layer:



Working with Masks

The brush and fill tools can be used to “paint” onto the mask. For example, select the Brush Tool (B)

then paint with black colour onto the mask to hide parts of that layer, i.e. make those parts

transparent.

TIP: Remember to select the thumbnail of the mask in the Layers panel before brushing, otherwise

you will be painting onto the layer itself.

The image above shows a mask being used to blend the Cardiff Castle layer with The Bay layer.

Looking at the mask thumbnail (inset) you can see the areas of Cardiff Castle in black are hidden

(transparent), allowing the contents of The Bay to shine through.

TIP 1: To just view the mask alone, hold down Alt and click on the mask thumbnail.

TIP 2: To temporarily disable a mask, hold down Shift and click on the mask thumbnail.



Using Masks with Selections

Masks can be used to save and refine selections. First, make a selection using selection tools of your

choice. When you are happy with your selection click the Add layer mask button at the bottom the

Layers panel. The selection is then turned into a mask; the area you have selected is white (visible),

the rest of the layer is black (transparent).

Brush tools can then be used on the mask to add or remove parts. Here we would use black to brush

the area beneath the student’s arm (to hide it) and white at the top of his arm to add back in parts of

his arm that were not selected properly.

Select and Mask (Refine Edge)

The Select and Mask tool (previously called Refine Edge) allows selections or masks to be fine-tuned

by tightening or loosening the selection at the edges. It is especially useful for difficult selections that

do not have defined edges, such as hair. When the Select and Mask button is clicked Photoshop

examines the edge of your selection and determines what needs to be included and what can be

excluded from the selection, but you can change this determination using the Properties panel and

Tools available in Select and Mask mode.



To refine a selection:

1. Make a selection with a selection tool of your choice. You should try to select your subject

as best you can, but it does not have to be a perfect selection.

2. Click the Select and Mask… button on the options bar:

Select and Mask Properties

The Properties panel appears on the right when in Select and Mask mode.

Set refinement

options

View Mode

Refine the edge of

a selection (radius)



The View Mode allows you to see your selection against different backgrounds, such as black, white

or over all layers. Changing the View Mode does not affect your selection, but can make it easier to

see exactly what is selected.

Radius specifies a distance from the edge of the initial selection that Photoshop should examine to

see whether content should be included in the new selection. Smart Radius - instructs Photoshop to

tighten up the radius size wherever possible, for example on well-defined edges such as arms and

legs.

The refinement options allow you to alter the selection:

Smooth - can be used to smooth out jagged edges.

Feather - blurs the selection edge.

Contrast - sharpens up selection edges by increasing contrast.

Shift Edge - moves the selection edge inwards or outwards.

Decontaminate Colors (Output Settings) - removes “fringing” by changing background

colours around the selection so that they match the colour of selection.

Select and Mask Tools

A variety of selection tools appear in the Tools panel when in Select and Mask mode, including the

Quick Selection Tool and Brush and a new tool: Refine Edge Brush Tool.

The Refine Edge Brush Tool is a brush-like tool that can be used to manually specify parts of the

edge to be included in the radius. To use the tool, brush over the parts of the image you would like

to be included. To restore the original selection, you can change the mode of the brush using the

Options bar (the negative symbol).

Refine Edge Brush Tool (R)

Quick Selection Tool (W)

Brush Tool (B)



Adjustment Layers

Adjustment layers allow image enhancements to be applied to an image in a non-destructive

manner. Adjustment layers do not change the image itself, they add the adjustment as a separate

layer. The settings for the adjustment can then be changed in future, or toggled on/off.

There are 16 different adjustment layers, we will explore some of the most useful in the rest of this

section. To begin let’s add a Brightness/Contrast adjustment layer to boost the contrast of an

image.

Adding an Adjustment Layer

The easiest way to add an adjustment layer is to use the Adjustments panel; simply click on the type

of adjustment layer you wish to add:

Once the adjustment layer has been added, you can change its settings using the Properties panel:



Working with Adjustment Layers

By default, adjustment layers apply to all layers beneath the adjustment layer. So, to alter the layers

that are affected by the adjustment layer, you can change the stacking order of the layers. In the

image below the Brightness/Contrast adjustment layer applies to the Student and Cardiff Met layers

(as they are below the adjustment layer), but not the Study at Cardiff Met or Blue rectangle layers.

Clipping Adjustment Layers

Adjustment layers can be clipped, or attached, to a layer. Clipped adjustment layers will only affect

the layer they are attached to.

To clip an adjustment layer use the clip button at the bottom of the Properties panel. Alternatively,

hold down the Alt key and click between the adjustment layer and the layer.



When a layer is clipped a square arrow appears next to the adjustment layer and the layer it is

clipped to is underlined:

Photo Filter

The Photo Filter adjustment layer applies a colour overlay to layers. It can be used, for example, to

add a cooling or warming effect to your layers. To begin, choose the Photo Filter adjustment from

the Adjustments panel:

Then use the Properties panel to choose the colour of the filter and its density (or intensity):



Hue/Saturation

The Hue/Saturation adjustment enables you to fine-tune the colours in your image. It allows you to

adjust the Hue, or colours in the image, the Saturation, which is the vivacity of the colours and

Lightness, which determines the amount of white or black in the colours. These values are

sometimes collectively known as HSL values.

The HSL values can be changed for a specific range of colours (e.g. Reds), or for all colours at once

(the Master setting in the drop-down menu). To use the Hue/Saturation adjustment layer, choose it

from the Adjustments panel:

Then use the dialogue to adjust the settings:

There a number of Presets available, or you can adjust the settings manually:

1. Specify the range of colours you wish to adjust by choosing an option from the drop-down

menu. Master changes all colours, or you could specify to adjust only the Reds in the image,

for example.

2. The Saturation and Lightness settings are quite straightforward, drag them left to decrease

the value, or right to increase it.

Choose a Preset

Specify the

range of colours

to change

Change the

sliders to adjust

HSL values

Colour

mappings



3. The Hue slider works by adjusting the mappings for the colours in an image. The colour

mappings are represented by the two bars at the bottom of the dialogue. The top bar is the

original colours, the bottom is the new settings. Drag the Hue slider to remap the colours in

the image; the original colour on the top bar will then become the colour that is directly

below it on the bottom bar. For example, you can change the yellows in an image to green

by: selecting Yellows from the range drop-down then dragging the Hue slider so that green

appears on the bottom bar below yellow on the top bar.

Levels

The Levels adjustment enables you to improve the contrast of an image by redefining the tonal

range. The tonal range is the variety of colours, or tones, in the image. The Levels adjustment

allows you to remap the tones in the range, for example by darkening the darkest pixels and

lightening the lightest pixels, this improves contrast and adds detail to parts of the image. This can

be done manually, or a Preset can be used.

To apply a Levels Preset:

1. Add a Levels adjustment layer:

2. Choose a Preset from the list, then click OK.



To adjust levels manually, the Levels histogram is used. But first, a quick note on terminology:

Shadows – are dark areas of an image

Highlights – are light areas of an image

Midtones – are the tones in the middle

The histogram is a visual representation of the number (or frequency) of tones in an image. The left

of the histogram represents the shadows, the right is the highlights and the middle ground depicts

the frequency of the midtones. The higher the level, the more pixels there of that tone. For

example, in the histogram below, you can see there are a lot of pixels in the midtone region, and

relatively fewer in the shadows and highlights.

To adjust contrast with the histogram, use the sliders below the histogram to adjust the levels:

a. Moving the black point tells Photoshop to make all pixels to the left of the slider

pure black.

b. Moving the white point makes all pixels to the right of the slider pure white.

c. Moving the middle (gamma) slider adjusts the midtones in the image.

When the black and white point sliders are moved Photoshop redistributes the tonal range between

the new levels to keep the transitions between tones as smooth as possible.

TIP: In images that lack detail in both the shadows and the highlights (such as the image above) you

would drag the black point to the beginning of the histogram and the white point to the end of the

histogram. A small adjustment could then be made to the middle slider, if necessary.

Black point

slider White point

Gamma slider

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