Specifications

The Digital Fine Print Course

Editing a Fine Print

Density Range:

Density range refers to the tonal or brightness range of the image and is not the same as

its colour range (or balance). Mode changing a colour image to a greyscale image changes

its colour values to density values. This represents the tonal darkness and lightness of

the print. An image's tonal composition may be different to its colour composition. For

example: A red rose may have the same tonality as the green leaves surrounding it, and

hence have a very low tonal contrast or density range, but a very high colour range or

colour contrast (red to green).

Colour Balance - Global:

Control over the global colour balance of an image is very important. In analogue colour

photography this was achieved either by a subtractive system (CMY filters), or by an addi-

tive system that mixed red, green and blue light. Photoshop (and colour monitors) also

use an additive system mixing red, green and blue colour channels.

Relative Colour Values - Curves:

Control of the RGB values for each pixel relative to any other pixel in the image is a very

important control in expressive colour print making. Curves allow every level of bright-

ness, from 0 to 255 to be individually adjusted with precision.

Photoshop Colour Correction Tool Caveats:

Curves while facilitating specific areas of the image to be identified and adjusted, only

permit 256 levels of adjustment, even when working in 16-bit. Locked down control points

on an RGB curve unfortunately change their value whenever other points are moved. That

is they do not remain locked down. The RGB curve also causes saturation increases rel-

ative to brightness decreases, which is the opposite of human vision and expectation.

Hue and Saturation (HSL) is an wonderful tool that also works with Lab images

Colour Balance settings can not be saved but have a Preserve Luminosity feature which

attempts to alter the colour balance without distorting the overall luminosity.

Selective Color offers CMYK controls while still effectively adjusting RGB curves. Neutral

colour balance can be easily modified, and the K slider controls density in colour.

Brightness and Contrast in Legacy mode clips the image’s density range, and therefore

has to be used carefully to prevent significant damage to the image.

11/50