Sharpening

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gian
Posts: 32
Joined: Wed Aug 28, 2013 7:00 pm

Sharpening

Post by gian » Wed Sep 11, 2013 5:16 pm

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

zedonet
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Posts: 1800
Joined: Fri Oct 06, 2006 8:02 am

Re: Sharpening

Post by zedonet » Fri Sep 13, 2013 8:07 am

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.

gian
Posts: 32
Joined: Wed Aug 28, 2013 7:00 pm

Re: Sharpening

Post by gian » Fri Sep 13, 2013 8:20 am

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.

gian
Posts: 32
Joined: Wed Aug 28, 2013 7:00 pm

Re: Sharpening

Post by gian » Fri Sep 13, 2013 8:24 am

I must specify that I am looking for a dedicated photo printing system under Linux, so text issues are not relevant to me.

zedonet
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Posts: 1800
Joined: Fri Oct 06, 2006 8:02 am

Re: Sharpening

Post by zedonet » Fri Sep 13, 2013 8:29 am

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.

gian
Posts: 32
Joined: Wed Aug 28, 2013 7:00 pm

Re: Sharpening

Post by gian » Fri Sep 13, 2013 8:46 am

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.

zedonet
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Re: Sharpening

Post by zedonet » Mon Sep 16, 2013 9:22 am

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.

gian
Posts: 32
Joined: Wed Aug 28, 2013 7:00 pm

Re: Sharpening

Post by gian » Mon Sep 16, 2013 7:28 pm

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.

zedonet
Site Admin
Posts: 1800
Joined: Fri Oct 06, 2006 8:02 am

Re: Sharpening

Post by zedonet » Wed Sep 25, 2013 8:40 am

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

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