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

[Helge Blischke]

I processed your png image (as I did last time) using the cupsfilter  
command and using the Zebra PPD (for getting the printer defaults).
The result is, as far as I can see, the same quality as the original  
image, though two conversion steps (png -> PDF -> cups-raster)
are involved. See
https://www.dropbox.com/sh/v6wjwi7pwk6wrdu/AAAkBcHRMSJ9-WELovHq7lY_a
You should print this file in raw mode to your Zebra printer or look  
at it using Michael Sweet's rasterview utility.

Helge

Am 10.07.2014 um 11:50 schrieb 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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