Canon Pro9000 ll colour shift noticeable in greys

[Emulator]

Hi PeterBJ

Now that is a well reasoned argument Peter, you may be right. Yes, it was landscape, left to right in both cases. I have two sets of refilled carts and I have the same effect from both sets. But there is no sign of the problem in normal colour printing.

I am printing through Photoshop Elements 8, sometimes using the Easyphoto Print Pro plugin, but these were entirely Photoshop. I think it was Rodbam who said he switches off "Photoshop controls colour management" and lets the 9000 do the controlling, to avoid this sort of thing. I must experiment further with this approach, because it would verify whether it is due to the carts.

I have gradually adjusted the colour controls in the profile to correct to the intended grey, but something else seems to take control and the effect persists.

Regards Ian

 

[Emulator]

A further thought Peter, when I print pure colour strips, I don't notice this effect.

Ian

 

[rodbam]

I think it was Rodbam who said he switches off "Photoshop controls colour management" and lets the 9000 do the controlling, to avoid this sort of thing.

I can't remember saying that & if I did it was old age talking
I always have Photoshop control the printer for colour work & for B&W I only use Easy Print Pro plug in. I do remember saying that when I let Photoshop control the printer for B&W I would get a colour cast but the B&W prints from the Print pro plug in are really neutral looking.

 

[Emulator]

Hi Rod

I like the abreviation, it adds a touch of wildlife to the image. I am surprised that you could feel your ears burning as far away as Aus.

It was round about post 20, 21 and we are talking about a greyscale problem, but in colour mode. So your advice is valid.

Regards Ian

 

[PeterBJ]

I would have ruled out profile issues as the cause of the color shift, as the printer/computer should not change profiles during a print job. But have a look at this: http://www.nifty-stuff.com/forum/viewtopic.php?id=4695

I think it is somewhat similar to your problem. Note the abrupt change in color compared to my uploaded image which shows a more gradual change, starting with banding before cyan quits, so maybe a magnifier can help in determining what is going on?

A test picture with grey bars can also be made in Microsoft Word or Open Office Draw. I wonder if such a test picture printed without involving Photoshop or other imaging software will show the same error?

 

[Emulator]

PeterBJ

Interesting, I explored your suggestion re MS Word and found somewhat similar effects on the greys. So I had a rethink and started at square one and have just produced this photo of a print using photoshop.

It looks to be an improvement. What do you think?

Regards Ian

 

[Emulator]

I have changed a number of aspects of the printing and profiling process to produce the print in the previous post and I will summarise them later.

The question of ink starvation is interesting. If you have too much ink available at the start of printing a strip (a very small reservoir), which then thins out as you progress, you have a similar effect to starting with the right amount and running into starvation. The difference would show between printing light shades and dark shades of the same colour. If lighter shades are more affected than dark, then it would be resovoir effect and if the reverse, it would be starvation. Looking at the cyan strips above, the lighter shade appears to show a slight shift, where as the darker does not, suggesting 'reservoir' effect. I think viscosity would come into the process as well, but I have no facilities to make accurate measurements.

Ian

 

[stratman]

Reservoir Effect?

I read your explanation but it does not make sense to me with the Canon CLI-8 cartridge. How is there "too much ink" and where is this ink? Why would lighter shades be more affected by this reservoir effect? Wouldn't the reservoir of ink delay printing issues and be less likely to affect the printing of lighter shades?

It all sounds like ink starvation - available ink is not being utilized for whatever reason. The issue then is one of timing of ink starvation in your example. More importantly, is the "fix" different for your proposed two issues?

 

[Emulator]

Hi stratman

The two sets of colour bars were printed on one sheet starting at the top. You may be able to see the 255 cyan displays a lightening of colour shade down the strip. The 186 cyan strip, which requires a greater flow of ink, printed immediately after, does not appear to lighten. If there is ink starvation how is the second strip not affected?

This, to me, indicates an initial excess of ink, rather than starvation. I am speculating that there is a very small excess in the cart/printhead after the printer has been idle for a short period, which gets consumed very quickly. The exact mechanism being something that remains to be explained!

Regards Ian

 

[The Hat]

Emulator

I am at odds with your explanation and dont agree with the theory of excess ink its frankly an impossibility.

This, to me, indicates an initial excess of ink, rather than starvation.
I am speculating that there is a very small excess in the cart/printhead after the printer has been idle for a short period,

The print head will deliver the exact amount of ink that is required every time or less if
there is a clogged nozzle, or a problem cartridge which is unable to provide the correct amount of ink when it's required.

If there is an excess of ink in your print head when your printer is idle then your cartridge has
a leak which would result in that cartridge emptying usually quickly and be very visible to you..

The two sets of colour bars were printed on one sheet starting at the top.

The two cyan colour bars are different in that your printer will use a combination of the other three colours
to make up the cyan you see printed; it just doesnt use the cyan ink alone.

Here is a selection of colour bars printed using only three colours as a demonstration on
how the print head delicately combines each colour to achieve the final result.