Different page coverage results using .PS vs. Screen Capture

[ndorf]

Has anyone besides me noticed a dramatic difference in page coverage results using the two different methods?

I did a test example whereby I printed a single page MS Word memo to a postscript file. When I used APFill to read the .ps file the coverage was 3%. I got the same result in both 600dpi printout (read-back into APFill at 300dpi) and 300dpi printout (read back into APFill at 300dpi).

Then, I printed hardcopy of the memo, and physically scanned it back to my desktop as an image file. Using a image viewer, and fitting the page to my 15" screen, I used APFill to again measure the page coverage. This time it was 10% (11% for the document printed and scanned back at 600dpi)

Which is the more correct coverage; 3% or 10%?

I did a similar experiment with an 8 1/2 x 14" legal sized document and got a 5% variance.

Any insights would be greatly appreciated.

[support]

PS file measuring is more accurate because of exact converting into bitmap.

When you measure PS file you can chose maximum dpi and get exact coverage. But when you are calculating from Screen all depends on your viewer. How it paints your page on the screen, it can paint letters approximately for best viewing, so you can use "Zoom In" APFill feature to see how inexactly it is.

So you get so dramatic diference because of low coverage. in this case very unessential smoothing set big diference, especialy if you use scanned images. If you are measuring pages with coverage great than 30% then diffrence is lower.

So if you want fast estimate ink coverage you can use screen capture feature. But if you want accurate calculating coverage you should use PS measuring.

[xvzolty]

I have a laser printer using CMYK toners. each of toners are marked as lasting 10000 pages at 5% coverage. I assume that reffers to 8.5 x 11 (letter size pages,) right?