Digital BW, The Print

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.