Joined: 20 Jul 2010 Posts: 3573 Location: New Zealand
Posted: Mon 07 Sep 2015, 00:57 Post subject:
Print quality variation between Slacko 5.3 and 5.6 [Solved] Subject description: Colour quality varies even using same driver
I use both Slacko 5.3 and Slacko 5.6 for printing colour documents to my Konica Minolta Magicolor 2300W printer but I get different quality results from each Slacko - even though I use the same driver and method of installation on both systems. I have made my tests using a live CD (no savefile) in each case.
I am hopeful someone can suggest what troubleshooting steps I can take to identify what is causing this different behaviour.
Here is the situation:
- I have no problems with the driver. It is a pet made available by rcrsn51 here and works perfectly on Slacko 5.3. I simply install the pet, use Cups admin page to discover the printer and it installs itself. Print quality is excellent for my needs.
- When I install this same pet on Slacko 5.6 I can install the printer (same method as above) and print quite happily but the text and images seem dark and "heavy". It looks as if way too much toner is being put on the page. It is so dark that images look as if they were taken without lighting.
- I tried using mtpaint to change the gamma value of an image and make it much much lighter before adding it to my document and printing it and was able to get reasonable results. The printed image looked much closer to how it should even though the onscreen image looked so washed out on screen that it appeared to have been taken in a snowstorm.
The pictures below offer comparisons to show what i am talking about:
The cups test page prints nicely from Slacko 5.3, but looks dark and lacking in halftones when printed from Slacko 5.6 (I have also included an image of a Brother 7820 black and white test page printed from Slacko 5.6 - it looks perfectly ok when printed on either system).
The dark image of my neice is showing how it printed from Slacko 5.6, even though it appeared normal onscreen. The lighter version of that image is showing how it printed out after I used mtpaint to lighten it so much that it was totally washed out on screen - but not so bad on the printer.
My interpretation of this is that there may be some sort of colour profile difference between the two systems affecting halftone printing - but I have no idea where to look. Unfortunately halftones are critical when printing most pictures.
There is a difference in Cups version - Slacko 5.3 is using cups 1.4.6 and Slacko 5.6 is using cups 1.4.8
Thanks in advance for any troubleshooting suggestions.
Cups test page from Slacko 5.6 looks dull and heavy - almost as if it is smudged. Note the dark colour wheel.
Cups test page looks great when printed from Slacko 5.3 - Note the gentle halftones in the colour wheel
This image was clear and perfect on screen but dark like this after printing
I used mtpaint to change the gamma, and made the image so light onscreen you could hardly see what it was.
Halftones good on MFC7820 from Slacko 5.6 or Slacko 5.3. No variation
Last edited by greengeek on Tue 08 Sep 2015, 02:24; edited 1 time in total
First of all I decided to "upgrade" the old ghostscript on Slacko 5.3 by using a Ghostscript 9.05 pet referred to by rcrsn51 third of the way down this post and sure enough once that was loaded to slacko 5.3 it gave the same darkened colour wheel as I was getting on Slacko 5.6
Next I decided to try a "dirty" downgrade from version 9 to version 8 simply by grabbing some of the Ghostscript files from Slacko 5.3 and grafting them over part of the ghostscript files in Slacko 5.6
This worked and the colourwheel returns to normal and printing of my colour document is excellent. I don't recommend such an incomplete method of changing ghostscript - especially if you run a savefile which would retain the changes (which i don't) but anyway it has worked for me to get my printing done so I have made a pet which can be applied to Slacko 5.6 to overcome the dark gamma.
I have found some web info regarding how to change ghostscript gamma but it is more complex than I can understand at present. I am hopeful that I may eventually be able to return to Ghostscript 9.05 (or higher) and coach it to set it's gamma correctly.
The "Ghostscript_dirtydowngrade" pet is available here
*** WARNING *** it would probably be a bad idea to use my hackpet on a normal Puppy setup (with savefile) as it will render your ghostscript abnormal and hybrid. Only use this if you know how you can return your system to normal afterwards
. Last edited by greengeek on Tue 08 Sep 2015, 15:48; edited 1 time in total
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