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Printer: Change a not supported setting ?

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brian_p
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Re: Printer: Change a not supported setting ?

#21 Post by brian_p »

By now you should fully understand and appreciate
  • Altering brightness has nothing to do with the printer model.
  • Altering brightness has nothing to do with the PPD (drvless or HP).
  • The only files that can be made brighter or darker are image files (jpg etc).
  • cups-filters has imageto... filters to manipulate images (e.g. imagetopdf).
  • A PDF cannot be made brighter or darker.
  • Most applications produce a PDF to send to the printing system.
  • The printing system by itself cannot convert a PDF to image format. It needs help.
  • Tea4CUPS can help if a user devises a script to use with a hook.
If I understand right, it would be possible in principle with "Tea4CUPS" and with a "script that must be written first". (?
Definitely! In my next post I will give you a command to use as part of a script.

These are options understood by imagetopdf:
  • brightness. The default is 100.
  • gamma. The default is 1000.
  • saturation. The default is 100.
  • hue. The default is 0. The range is -360 to 360.
  • colorspace. rbg, cmyk or gray.
Last edited by brian_p on 2021-03-28 16:58, edited 1 time in total.
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brian_p
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Re: Printer: Change a not supported setting ?

#22 Post by brian_p »

Testing the effect of the imagetopdf options by printing is wastefu of
paper and ink. It is much more efficient to use what the printing system
provides. The basic command to use is

Code: Select all

/usr/sbin/cupsfilter -o colorspace=rgb -o brightness=170 in.jpg out.pdf
out.pdf can be viewed and, if suitable, sent to the printer with

Code: Select all

lp -d PRINTQ_NAME out.pdf
or by printing from the viewing application.
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Ihamed
Posts: 34
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Re: Printer: Change a not supported setting ?

#23 Post by Ihamed »

OK. Do I understand right that ...

1) To get what I want, Tea4CUPS must convert a PDF (because most applications produce a PDF) into an image format.
2) After, to get this image brighter, this image must be converted via Tea4CUPS- script. In this script must be a command that uses an imageto* filter.
3) After, Tea4CUPS can send the converted image to the printer.

Right?

brian_p
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Re: Printer: Change a not supported setting ?

#24 Post by brian_p »

Ihamed wrote:OK. Do I understand right that ...

1) To get what I want, Tea4CUPS must convert a PDF (because most applications produce a PDF) into an image format.
Correct. The PDF cannot be allowed be allowed to enter the printing
system after being sent to it. Intercept it and process before sending
it on its way. Perhaps "Enforcing number-up=2 Printing (2)" helps.
2) After, to get this image brighter, this image must be converted via Tea4CUPS- script. In this script must be a command that uses an imageto* filter.
Indeed. Perhaps my previous post helps.
3) After, Tea4CUPS can send the converted image to the printer.
Exactly. But beware. A multiple page PDF would require a script to
handle that, depending on how the input PDF is handled.
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Ihamed
Posts: 34
Joined: 2021-01-31 09:23

Re: Printer: Change a not supported setting ?

#25 Post by Ihamed »

Do I also understand right, that I will have to build something like a "virtual printer" with Tea4CUPS.

And at the end, when all is implemented and I want to print brighter, then I
-open an application. After I
-open the file, that I want to print. Then I
-choose for example "menu->file->print" in this application and select the "virtual printer"
and all steps run in the background and I get a brighter print.

Right?

brian_p
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Re: Printer: Change a not supported setting ?

#26 Post by brian_p »

Ihamed wrote:Do I also understand right, that I will have to build something like a "virtual printer" with Tea4CUPS.

And at the end, when all is implemented and I want to print brighter, then I
-open an application. After I
-open the file, that I want to print. Then I
-choose for example "menu->file->print" in this application and select the "virtual printer"
and all steps run in the background and I get a brighter print.

Right?
That's the correct idea.
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Brian.

Ihamed
Posts: 34
Joined: 2021-01-31 09:23

Re: Printer: Change a not supported setting ?

#27 Post by Ihamed »

Thank you.

Other question of interest:
You always call "imagetobrf", "imagetops", "imagetoraster", "imagetoubrl" and "imagetopdf" filters. And they are in a folder that is called "filter". But for example "imagetopdf" can convert an image for example in relation to brightness.

So why are they not called converters? And why do they not be in a folder with the name "converters"?

What is the difference between a filter and a converter?
Or is a filter the same like a converter and this are only different names for the same thing?
Last edited by Ihamed on 2021-03-29 13:13, edited 5 times in total.

arzgi
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Re: Printer: Change a not supported setting ?

#28 Post by arzgi »

Code: Select all

$ apt-file search imageto
cups-filters: /usr/lib/cups/filter/imagetobrf
cups-filters: /usr/lib/cups/filter/imagetops
cups-filters: /usr/lib/cups/filter/imagetoraster
cups-filters: /usr/lib/cups/filter/imagetoubrl
cups-filters-core-drivers: /usr/lib/cups/filter/imagetopdf

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