Eccentric circles when copying

[OMD-227]

Try changing the auto exposure mode to something else (text, photo, map, copy of copy etc etc).

I vaguely remember a case like this years ago. A client had an adobe indesign document that copied with very shifted colors. It was almost like a registration fault, but it was only happening on this particular document, everything else was perfect.
A bit of research on various photoshop & indesign forums lead me to find that you can create an image within indesign at 16bit color. The copier in use had a 1bit scanner. Using auto exposure, the scanner was picking up various & extra colors within the image (as the black line of the drawing was actually a 16bit, multi-layered, multi-colored line, appearing as black to the human eye).

Changing AE to Text/Printed Photo enabled it to copy correctly.


A long shot maybe, but as soon as I read the part about photoshop and saw the sample, it rang all the bells. I bet it doesnt do that sort of copy with any other document.

[Shuelin]

CBMWilson: I dont disagree, and the copy of a copy is bad. but what is happening is random. the above is one sample If i was to copy it again, the skew is in a cmpletely different spot, without moving the orignal on the bed. It is strange.

[Shuelin]

WAZZA: all i have to say is holy crap. it worked. I just tried setting the resolution at the highest setting and then text only black and white. this was on an older officejet and it works, it is as close as I need it to be. I will try this on the laser mfp in the earlier post over the weekend.

thanks again
shawn

[OMD-227]

Nice fix bro!

I knew my tedious forum-scouring research would come in handy one day....

[blackcat4866]

Impressive! Great work wazza! I'll remember that.

I've dealt with the normal distortion you can get from any analog scanner. In my attempts to get the analog engine and scanner to perfectly register and with minimal skew, I discovered that there of areas of the image that tend to have more distortion than other areas. If you can envision a clock face on a letter portrait page, the areas at the center, radially out at 12, 3, 6, and 9, all can be registered perfectly every time. The areas radially out from the center at 1:30, 4;30, 7:30, and 10:30 experience the most distortion, but on any single machine remains consistent copy to copy.

The test pattern I created for centering, skew, voids, and registration, has a vertical line exactly centered 108mm from each edge, and a horizontal line exactly centered 139.5mm from each edge. If you can get these lines exactly centered, exactly registered, without skew, and perfectly aligned when viewed through a duplex copy, that is as close as you can get. The other areas will experience some unavoidable distortion, usually less than 1/2mm when using a fine grid original, and more exaggerated the further you get from dead center. My test patterns that had lines 10mm from each edge showed the most distortion, and were nearly impossible to get a "perfect" adjustment. Incidentally, most manufacturers write right into the specs +/- 1.5mm is normal variation of image registration. In most cases I've pulled it in within 1/4mm, many dead on.

I haven't made the same comparisons on digital scanners, but I suspect there would be similar results. Maybe one of you optics experts can explain the "why".

=^..^=

[OMD-227]

Its a grand day indeed when you are impressed by something Dave.
I shall savour this moment for a few minutes.......................................