[cups] Mac OSX with CUPS 1.7.2 Printing fuzzy on Zebra GK420d

[Matthew Warren]

Hi Helge,

Really appreciate your advice on this matter, its driving us a little mad.

We did a test with one of the images and converted it to 203 DPI with b/w colour and saved as PNG, you can see it here https://www.dropbox.com/s/agchkmr7cl9xyz9/1st%20CLASS-jade.png

But the result is terrible, its very blurry https://www.dropbox.com/s/c7obxxcokkn35ps/IMAG0064.jpg

Matt

On 8 Jul 2014, at 14:23, Helge Blischke <HelgeBlischke at web.de> wrote:

> 
> Am 08.07.2014 um 13:48 schrieb Matthew Warren:
> 
>> Thanks for the reply and advice!
>> 
>> I printed another label and tried to include all the log stuff again https://www.evernote.com/shard/s273/sh/17d4d1ab-d712-4e10-88a9-5465a0bc0aaa/68062e9ddeeaad629c7f0017dd00fba9
>> 
>> Here is one of the original images, it has a DPI of 300, 356x869 pixels, RGB, Depth is 9
>> 
>> https://www.dropbox.com/s/2pgmcwj2z3i3pg3/PPI%201st%20Class.jpg
>> 
>> I've had a look at the filter you suggest, but that is going beyond my technical skills to get that working, do you know of any guides (above and beyond the readme) that show how to install filters?
>> 
>> 
>> On 8 Jul 2014, at 12:23, Helge Blischke <HelgeBlischke at web.de> wrote:
>> 
>>> 
>>> Am 08.07.2014 um 12:01 schrieb Matthew Warren:
>>> 
>>>> Machine:  Macbook Air
>>>> OS: OSX 10.9.3
>>>> CUPS: 1.7.2
>>>> Driver: ZPL
>>>> Printer: Brand new Zebra GK420d
>>>> 
>>>> 
>>>> 
>>>> We are trying to print PDF shipping labels, these labels have high quality JPG images in them as well as text and a barcode. Here is the label https://www.dropbox.com/s/2bygmavx0tw17s2/label%20%2823%29.pdf
>>>> 
>>>> Problem: The quality is very fuzzy/distorted. The JPG images are the worst effected but even the barcode and text are not good. See photo here https://www.dropbox.com/s/in3g64f8g69sk2d/IMAG0062.jpg
>>>> 
>>>> Here is the error log from CUPS https://www.dropbox.com/s/88ipbc4bmtjsqho/error_log
>>>> 
>>>> Printer works fine on Windows machine.
>>>> 
>>>> We have replicated this problem on multiple Mac machines (our customers) with the same setup as above.
>>>> 
>>>> We have printed hundreds of test trying various different solutions and we have only had any improvements when we load the PDF into Gimp and convert it to 1 bit colour (black/white) with a DPI of 203 save it in XCF format, its better but not perfect.  If we then save that into PDF format again, it makes it worse again.
>>>> 
>>>> We have tried converting to other formats like SVG/EPS without luck.
>>>> 
>>>> I can live with the text quality but the images and barcode are not good enough for the courier.  Problem seems linked to CUPS/Zebra when it converts the PDF to its 1 bit colour and does not do a great job, but I am no expert.
>>>> 
>>>> Desperate for some help/advice and I would be extremely grateful for any!
>>>> 
>>>> 
>>>> 
>>> 
>>> It's a pity that your error_log snippet lacks the initial messages of the job in question; so the messages regarding what
>>> filters are used is missing. And, could you please tell more details about the original images (color space, resolution, etc.).
>>> My suspicion is that the default image to pdf filter, cgimagetopdf, and the filter to convert the PDF to cups-raster, cgpdftoraster,
>>> both use inappropriate settings with respect to color space(s) and device resolution.
>>> 
>>> Perhaps you could try the filter from
>>> http://sourceforge.net/projects/cupsaddons/files/filter-gstoraster/
>>> which has been heavily testede with diverse Zebra printers.
>>> 
>>> Helge
>>> 
> 
> Matthew,
> 
> on the short term, I suspect there is nothing you can do really. I simulated (with the cupsfilter utility) printing your image
> which my gstroraster filter and got essentially the same nonsatisfactory result.
> 
> A more detailed analysis showed that:
> (1) the source image has a resolution of 300 x 300 pixel, and the destination resolution of the printer is 203 x 203 pixel.
> (2) the source image colorspace is RGB, and the desination color space is b/w
> (3) the image within the PDF has the attribute "/Interpolate true".
> Thus, the source image has to be converted from 300x300 dpi RGB to 203x203dpi b/w, which almost certainly
> (and, in this case, in reality) leads to jaggy edges in the destination image.
> 
> The best approach, I think, would be to design the source images as b/w images with the destination resolution.
> 
> Helge
> 
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