Re: Photo Print Quality issue Canon G2000 series

On Wed, Dec 30, 2020 at 7:20 PM Jonathan Ing <[email protected]> wrote:
>
> Hi Gernot,
>
> Thanks for this wonderful explanation - I have no background in tuning drivers before so this makes a LOT of sense! One question I have is then is there any resource or guide for CUPS density controls? For example, if you see x, y or z, increase or decrease this parameter?

Hi Jonathan,
Not really, that is general CUPS information, I guess searches are
your best bet for what people have been doing for their particular
purposes.
As I wrote, it is a matter of extensive experimentation to work out
per media type at least, and most likely per resolution mode (used for
that media), what density corrections are required for each ink for
different hue, saturation, and value for each colour, and combination
of colours. You could start with a strip of black ink printing evenly
from 0% to 100% intensity, and see if you can get an output that
matches this. Some areas might need more careful tuning.
Then go on to cyan, then magenta, and finally yellow, which is hardest to see.

PS quick addendum, the plus Glossy II can use the other 2 photo modes
as well, the mode one I listed is solely useable by plusPhoto II
though.

Best regards,
Gernot Hassenpflug

> Thanks!
>
>
> On Wed, Dec 30, 2020 at 4:57 AM Protea Wines Japan <[email protected]> wrote:
>>
>> On Wed, Dec 30, 2020 at 12:20 AM Jonathan Ing <[email protected]> wrote:
>>>
>>> Hi, I am using the gutenprint v 5.3.3-4 on Ubuntu 20.04-1 and I notice that when printing photos (I am using 4x6 glossy, photo mode) and pictures have a low bitrate look to them... almost pixelated. I have set DPI to max 600x600 and nothing seems to help. Not sure if this is a potential bug?
>>
>>
>> Hello,
>> I am sure photo printing will not be good without some serious tuning of densities in CUPS, since the Canon driver does not include any calibration of colours.
>> However, maybe you can get better results if I explain the process, what you are saying about resolution is not really how it works.
>>
>> Firstly, the Canon printheads only have resolutions of 300dpi or 600dpi (some have a single mode that is at 1200dpi).
>> So "setting resolution to X dpi" is not what determines the quality.
>> The firmware uses the physical printhead resolution, multi-pass printing and complex algorithms making use of the available physical inks, to print at some "effective resolution".
>> The above process, and/or the possible quality, are different for each media type.
>>
>> Thus, when you select a resolution, you are not seeing a simple "X dpi" name for the resolution,
>> what you see is a "resolution mode" name, such as "High quality (600 DPI)", for example.
>> Each media type has several possible resolution modes associated with it, and hints are given in the drop-down, so that users do not attempt to use, say, plain media modes, with photo media, or vice versa.
>> If a resolution mode is chosen that the firmware does not know about for a particular media type, the printer will generally not print.
>>
>> So to prevent non-printing, if a non-compatible mode is selected in the Canon driver, then there is a forced selection to a similar quality mode accepted by the media.
>> As a result, depending on the other options apart from media type (e.g., double-sided printing), you might not be printing with the mode you think you selected.
>> The only way to be sure is to check the debug logs (setting them up in the CUPS interface).
>>
>> The G1000, G2000, G3000 share a common driver, with the following resolution modes available:
>>
>> A. For plain media
>>
>> 600x600 DPI HIGH
>> 600x600 DPI
>> 300x300 DPI
>>
>> B. For plus Glossy II only
>>
>> 600x600 DPI PHOTO HIGHEST plus Glossy II
>>
>> C. For other photo media
>>
>> 600x600 DPI PHOTO HIGH
>> 600x600 DPI PHOTO
>>
>> D. For envelope and hagaki (postcard) media
>>
>> 600x600 DPI HIGH (Env/Hagaki)
>> 600x600 DPI (Env/Hagaki)
>>
>> If you are trying one of the photo media resolution modes, and it is of poor quality, the tuning of the density of individual inks is probably way off.
>> Tuning is a lot of experimental effort, but you can try with the CUPS density controls for the different channels to see if you can improve matters.
>>
>> Best regards,
>> Gernot Hassenpflug



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