TONE REPRODUCTION ANDY WILLIAMS

AN ifra PUBLICATION

Contents

Preface 9

Acknowledgements 9

1. Introduction to tone reproduction 1 I 1.1 The reduced tone range of the reproduction 11 1.2 Classification of originals 1 1 1.3 How to provide a realistic reproduction of the original image

when it is not possible to reproduce the same range of tones 12 1.4 How to separate tone reproduction from colour reproduction 12 1.5 How to measure tone reproduction in the original or in the print 13 1.6 Selection of the greyscale 13 1.7 How is a tone curve drawn 15 1.8 The digital 'on-screen' densitometer 15

2. How does the tone reproduction curve relate to the scanner (or camera) and to the print 16

2.1 Tone compression on the highest bils-per-pixel data 16 2.2 Colour computation should come after

tone compression and colour correction 17 2.3 Flow chart for integrating tone reproduction

into the colour separation process 18

3. Preferred tone reproduction 19 3.1 Research on preferred tone reproduction curves 19 3.1.1 Density 20 3.1.2 Gamma 20 3.1.3 Munsell system 20 3.1.4 CIEL* 20 3.1.5 Jorgensen 21 3.1.6 Bartleson and Breneman - a visually linear scale for tone reproduction 21 3.2 High key and low key originals 22

4. General conditions influencing good tone reproduction 23 4.1 Standard viewing conditions 23 4.2 Good 3-colour greybalance 24 4.3 Colour correction and tone reproduction 25 4.4 Screen dot shape 25 4.5 Minimising contrast loss in the scanner - Hare 25 4.6 Standard repro densities 26 4.7 Maximum density (Dm,ix) 26 4.7.1 Increased Dmax for monochrome work 27

5. Image-specific settings for the scanner and imagesetter 28 5.1 Input resolution 28 5.2 Kodak Photo CD 28 5.3 Output resolution 29 5.4 Setting the highlight and shadow points 29

© 1FRA, Darmstadt

5.4.1 Setting the highlight point 29 5.4.2 Setting the shadow point 30 5.5 Size of the reproduction 30 5.6 Artificial intelligence 30 5.7 The black gradation and Grey Component Replacement (GCR) 31

6. Tone reproduction using Photoshop 32 6.1 Levels - the pixel histogram 33 6.1.1 Input levels 33 6.1.2 Gamma control setting 35 6.1.3 Output levels 34 6.1.4 Manual setting of the middle and end points within the image 36 6.1.5 Modifying the si/.e of the eye dropper 36 6.2 Curves - the tone gradation curve 36 6.2.1 Using the eyedropper for checking the film dot sizes 37 6.2.2 Restricting the tone range of the reproduction in Curves 37 6.3 Brightness/Contrast 38 6.4 Transfer Functions 38 6.4.1 The Transfer Functions for colour images 39 6.4.2 The Transfer Functions for black and white images 39 6.5 Exporting Curves into third-party software 39 6.6 Dodging and Burning 40 6.7 Guidelines for setting up curves 40 6.8 Photoshop 'plug-ins' 40

7. The program Tonmax 41 7.1 Program setup 41 7.1.1 File name 41 7.1.2 Type of original copy 41 7.1.3 Format for the results 41 7.1.4 Greyscale values 41 7.1.5 Viewing conditions 42 7.1.6 Highlight and shadow points of the original 42 7.1.7 Bend... 43 7.1.8 Dmin and Dm,x of the printing process 43 7.2 Obtaining the target densities 44 7.3 Prepress procedure 44 7.4 Press and post-press procedure 44 7.5 Tonmax summary 47

8. Suggested procedure for normal production 48

9. Automating production processes 49

10. Future developments 50

11. Conclusions 51

12. References 52

Appendix 53

© IFRA, Darmstadt