THE REPRODUCTION OF BOTANICAL ART - Page 3

Difficult Reds

TOP: The troublesome Cadmium reds and oranges. The as-scanned, profiled and then the hand-corrected red is shown inside the white marker.

No, we are not on the snooker table, we are talking red pigments! Lukman had experienced some difficulty in reproducing the popular pigment ‘cadmium red’. Differentiating between subtle changes of tones with these reds had been a particular problem with differences in originals not being reflected by differences in the prints made from scans. We decided to investigate in some detail. Lukman painted a set of swatches for analysis and these were measured using a spectrophotometer and then measured again after a variety of scanning options. The colours chosen were Windsor and Newton’s, Cadmium Orange, Cadmium Red, Alizarin Crimson, and a final swatch that was a mixture of the last two. The spectral analysis showed quite high metamerism in the pigments (see table), the values between 11.9 and 15.7 jeopardising any hope of really accurate reproductions for all lighting conditions. The scan of the swatches also enabled us to create a blizzard plot of the pixels so that we could superimpose the printer profile and study the colorants relative to the gamut boundaries. The nature of the problem now becomes evident – the colourants are well divided by the scanner, with relatively little overlap, but much of the colour is some way out of gamut. What we observed in the prints was a compression of saturation as the values were brought back into gamut for printing. Changing to another printer and to a media with a much higher gamut volume did little to alleviate the matter, these cadmium-based pigments are quite intense. It remains to be seen whether the new Epson ‘880’ series of printers with Vivid Magenta K3 inks can make any inroads into the deficit; it is not all that likely, as the 12-ink sets of both Canon and HP had a relatively small influence.

BELOW: Almost the entire flower head is out of gamut for this vibrant amaryllis.

ABOVE : The blizzard plot shows that the scanner is capable of differentiating the reds quite well.

ABOVE : The blizzard plot over-layed with the Gamut of the printer and paper combination chosen shows that the tones are predominantly out of gamut. The visual effect was that the inkjet print looked a little duller than the original.

BOTTOM: Even these seemingly inocuous reds are out of gamut for UltraChrome K3 inks and fine art papers.

Photo Quote: The camera is an instrument of detection. We photograph not only what we know, but also what we don't know. - Lisette Model