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mounaiban / captdriver

Driver for Canon CAPT printers
GNU General Public License v3.0
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Canon LBP-2900 prints with low density #33

Open artvolk opened 9 months ago

artvolk commented 9 months ago

Hi, first of all, thanks for the hard work on supporting obscure hardware! :)

I've got the driver working Ubuntu 23.10 x86_64 (running in Proxmox) (as a side note on Alpine 3.19 armhf (Raspberry Pi W) I've run into this issue: https://github.com/mounaiban/captdriver/issues/8).

The problem I have though is that all prints via CUPS and captdriver have less density (black text is gray) compared to printing via MacOS or Windows drivers with the printer attached directly via USB. I can observe this behavior for both vector PDFs or documents printed from LibreOffice.

I've had a quick look into CUPS options and captdriver source code, but haven't found any knobs to turn. Did I miss something obvious?

Thanks in advance!

mounaiban commented 7 months ago

You're not alone in finding CUPS printouts a little lighter than expected. There's a comment, on either Alexey's original repo or mine, that mentions this too. However, I can't seem to find it at time of writing.

The only printer-related control for darkness we know is Toner Density, this is communicated to the printer via the 0xD0A0 command, bytes 8-11.

Otherwise I'm suspecting differences in raster image processors; GhostScript (which CUPS uses as an RIP) may have a lighter gamma curve than the proprietary RIPs used in macOS and Windows. I haven't been able to verify this claim, but you might be able to if you have old, low spec printers that are supported in Linux, Mac and Windows.

Emphasis on old, because I suspect many new printers to have built-in RIPs and therefore produce the same results regardless of the OS the job comes from.

artvolk commented 7 months ago

Thanks for the response!

goatastronaut0212 commented 2 months ago

I also have the same problem in this, but I don't have many clues about this. Is there any way to fix this issue?

artvolk commented 2 months ago

I haven't find any so far.