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Sharpening

Posted: Wed Sep 11, 2013 5:16 pm
by gian
hello, All,

I would like to know if TP has a sharpening tool.

I think that sharpening should be the last pixel destructive action before the final destination, the paper.

Because TP resizes the image based on the paper size of the print, I do not want to sharpen my tiff before printing.

thanks for reading,
-Gian

Re: Sharpening

Posted: Fri Sep 13, 2013 8:07 am
by zedonet
Hello,

TurboPrint doesn't sharpen images during printing.

Some Windows drivers had the option to sharpen bitmap images - some people liked it, others hated it. Text must not be sharpened, otherwise a "halo" will be visible around characters. Under Linux, the driver receives the whole page as a large bitmap image - sharpening is difficult to implement, because it is not evident which parts of the page have to be sharpened.

Re: Sharpening

Posted: Fri Sep 13, 2013 8:20 am
by gian
Thanks for your kind reply.

The problem is, I don't know the *exact* pixel size the image will have when TP scales it for printing.

If TP did not scale it, I could sharpen the image myself.

This is why I always got astonishing results with Qimage (for Window$, doh!): it scales && sharpen at once.

Re: Sharpening

Posted: Fri Sep 13, 2013 8:24 am
by gian
I must specify that I am looking for a dedicated photo printing system under Linux, so text issues are not relevant to me.

Re: Sharpening

Posted: Fri Sep 13, 2013 8:29 am
by zedonet
Sharpening should probably be done by the photo print application - Qimage is also a photo print software, not a printer driver.
Maybe we can add such an app to TurboPrint in the future.

Re: Sharpening

Posted: Fri Sep 13, 2013 8:46 am
by gian
It's not clear to me how the job is shared between the printing app and the driver.

If you use Gimp for printing, is scaling done by Gimp or Turboprint?

If scaling is done by Gimp, then I would expect to have an option to sharpen in the print menu.

Else it should be the driver to care for the last step.

Re: Sharpening

Posted: Mon Sep 16, 2013 9:22 am
by zedonet
The application sends data in Postscript or PDF format which usually contains the original unscaled image plus scaling information (= image dimensions on the printed page). Scaling is done by a software component called "Ghostscript", the Linux Postscript & PDF interpreter. The printer driver receives a large bitmap that contains the image scaled to printer resolution.

Neither Ghostscript nor the printer driver knows if the page contains data that needs sharpening. In my option, such an option could be present in the application's print dialog.

Re: Sharpening

Posted: Mon Sep 16, 2013 7:28 pm
by gian
so when I tick the box "borderless print" in the Gimp-turboprint driver, Gimp will adjust the scaling to match?

Will it scale it twice, or just do it once?

I wonder if Gimp would be so clever to scale the unsharpened image, and then apply sharpening.

Or, if ghostscript has sharpening settings itself.

Re: Sharpening

Posted: Wed Sep 25, 2013 8:40 am
by zedonet
The "borderless print" button adjusts scaling in the same way as you can also adjust manually in the print dialog, the image is only scaled once.
As far as I know, Ghostscript doesn't have sharpening