More on Epson's use of GLOP
2005-03-07 by Bob Frost
When some of us were recently discussing Epson's use of GLOP (Gloss Optimiser) in the R800, Koloshor suggested that the only way to resolve the matter was to look at a print file and see which inks were used where. With Roy Harrington's help, I've done that as follows. I initially started looking at grayscales, but found it decidedly difficult to tell when the printer was switching from printing one patch to the next, because of the nature of Epson's microweave. So I made a series of 25 simple images, each containing a 1" square of a gray value (in increments of 10 from 255 - 5 (and 0)). These images were all in rgb and were printed with Printer Color Management set in PS and ICM set in the driver, with GLOP on Auto, with PhotoRPM as the resolution, and Premium Glossy as the paper setting. The 25 images were printed to files from Photoshop, decoded, and then output as txt files. Results Only Photoblack was used at 0/0/0 and 5/5/5, but at 15/15/15 magenta, blue, cyan, and yellow were used as well. The amount of photoblack decreased steadily up to 105/105/105, and was absent from 115/115/115 upwards, while the amounts of magenta, blue, cyan and yellow increased steadily from 15/15/15 to 105/105/105. Red was not used anywhere. Glop was not used until 105/105/105, where it's use overlapped with the disappearance of photoblack, and its use increased from then on to 255/255/255, while the amounts of magenta, blue, cyan, and yellow decreased steadily. At 255/255/255 only GLOP was used. Conclusions So we can see that in the darker half of the grayscale, the glossiness of these inks is entirely attributable to the inks themselves, NO GLOP is used. While in the lighter half of the grayscale, as the glossiness of the inks decreases, due to reduction of ink load, the use of GLOP increases directly to compensate for this, until at 255/255/255 the patch is pure shiny GLOP. A knowledgeable Epson person at the Focus on Imaging Exhibition last week told me that the HiGloss inks were more glossy because they had altered the coating on the pigment particles, and put in the pure GLOP to compensate for lack of ink in the lighter patches. Bob Frost.