Black ink consumption in grayscale/gray photo modes

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t-dome
Posts: 5
Joined: Tue Jun 14, 2011 9:24 pm

Black ink consumption in grayscale/gray photo modes

Post by t-dome » Tue Jun 14, 2011 10:14 pm

Hi,

I have a Canon iP2700 printer (with two cartridges - one black and one with CMY colors) and Turboprint 2.20-1 demo installed. I've discovered that printing black and white texts in "Grayscale Photo" mode seems to consume much less ink than in "Grayscale" mode according to the ink counters. Only black ink is used.

The outputs in the two modes look 99.5% identical but "Grayscale Photo" is printing about three times slower. Edges are a tiny little fuzzier when looked through a magnifying glass, so the overall quality is a little worse than in "Grayscale" mode, but it consumes less than half as much ink; at least according to the ink counter.

My question: is the ink counter correct? Judging from the printouts I would say there is no way, because there is practically no difference in quality. But even 25% less consumption would be great, so can anyone tell me if those two modes do indeed use a (much) different amount of black ink? I repeat, the color cartridge is not used (see the example below).

How to reproduce:
-open for example http://www.gnu.org/licenses/quick-guide-gplv3.pdf with Okular (the default PDF reader in KDE) and go to the print dialog
-only select page 3, because there are no colors
-go to printer settings -> Advanced, and check these settings:
Media Type: Plain paper
Print Quality: 2 - 600 dpi
Color Rendering Intent: "Perception Photo" (this setting doesn't matter in B/W printouts, I've also tried "Perception Inksave")
Color Mode: Gray Photo

All other settings are the default ones:
Page size: A4, Color space: Apple RGB (bright), Dithering: Error Diffusion.

(In Okular's print settings, it doesn't matter if you select Color mode or Grayscale mode, because there is no colored text on page 3.)

Result: 1911 of black ink used

Now, if you print the same page with "Grayscale" as Color Mode instead of "Gray Photo", the result is 4277.

Thanks

zedonet
Site Admin
Posts: 1800
Joined: Fri Oct 06, 2006 8:02 am

Re: Black ink consumption in grayscale/gray photo modes

Post by zedonet » Wed Jun 15, 2011 8:42 am

Hello,

did you also verify that the color inks were not used in Grayscale Photo mode? In Photo mode often color inks are added for mixing gray tones, in order to make prints less grainy and achieve darker blacks.

t-dome
Posts: 5
Joined: Tue Jun 14, 2011 9:24 pm

Re: Black ink consumption in grayscale/gray photo modes

Post by t-dome » Fri Jun 17, 2011 7:49 pm

Yes, the color cartridge was not used in both modes. There was only black text, and either there was no antialiasing used or the antialiasing was not using "grey", somehow.
zedonet wrote:Hello,

did you also verify that the color inks were not used in Grayscale Photo mode? In Photo mode often color inks are added for mixing gray tones, in order to make prints less grainy and achieve darker blacks.

zedonet
Site Admin
Posts: 1800
Joined: Fri Oct 06, 2006 8:02 am

Re: Black ink consumption in grayscale/gray photo modes

Post by zedonet » Mon Jun 20, 2011 2:59 pm

I could verify your results:

The ink amount that is displayed is too high in "b&w" and "grayscale" mode, the numbers reported in "color" and "gray photo" mode are correct.
The actual ink amount is the same. In gray "photo mode" the printer operates in a slower print mode (more print head passes with less ink applied per pass) which results in less visible "banding" but also less sharper text.

We will correct ink amount display in one of the next TurboPrint releases.

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