articles/Digital/colouradjust3-page5
by Mike McNamee Published 01/01/2003
One interesting test was to determine how accurately your Editor could adjust images on a calibrated screen with and without aids. In the first test I was able to match the image on screen and my own skin tones (in a mirror) to within 1.8 Delta E of each other. Without any points of reference I was able to get two independent images to within 7.8 Delta E of each other. Matching two images side by side on screen I was able to get the images to within1.4 delta E of each other. To put these values in perspective, the original print was 16.4 Delta E out, 4 is top class proofing quality and typical unprofiled inkjet printers can make averages of between 9 and 15 delta E points. The experiments confirm what is well known - that the eye is a very good comparator but no quite so good without points of reference. The subject of the round trip colour accuracy is something we are going to revisit later in this series.
Above: The main image is badly lacking in dynamic range. Note that the histogram does not extend to either end of the tone scale. Dragging the input sliders inwards from the edges improves the image as shown by the smaller inset.
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