Blacks shifting to greenish under daylight?

[Ink stained Fingers]

If you try to print 'gray' as a mix of colors you would have to 'white balance' the output, the ratio of the CMY colors against the color temperature of the ambient light. If you adjust your colors to a neutral - gray - look at daylight it'll look brownish red under lamp light. But to do it this way it may look less irritating since a warmer tone of gray at lamp light at a lower brightness looks less irritating than the greenish cast at daylight at a much higher brightness. So try this - adjust your image to gray - turning color saturation to zero whatever other tools you have in your editor for this purpose and then change the color temperature of your image so that you get a 'gray' looking output at daylight - it may have a strong cast on the screen. Softproofing won't help you much.
There is a reason that you can select different paper types in the driver, it adjusts the output taking some properties of the paper into account which you selected - mainly the black level and the related contrast range, ink saturation limits and such, it's a kind of base line profiling. You can play with these settings to see if it prints better this way or another way.
This is not a problem specific to the L805 but it is a general limitation when trying to mix colors to gray - it just works for one light condition. If you want to print with real gray inks you would have to switch to special inks for this purpose such as the Piezographic inks.
You can try another option available in the driver - the grayscale option - try this - it will most likely use the black ink only if you select normal paper or inkjet paper, not glossy paper; it will dither grayscale tones with the black ink only, the print may look a little bit more coarse than with the standard settings, but be aware - even the black ink is not neutral , and this will become visible at lighter grays, it'll tend to a blueish violet tone - most likely - on glossy paper. So there are several steps you can test to find out which give the best look overall for you.

 

[glasseye]

Excellent, ISF. Thanks for the clarification. I'll do a bunch of tests changing media targets and input file colour balance until I get something better. A print that looks a little red under incandescent is far preferable to one that looks green in daylight. It is truly a horrid green.

Interestingly, my pigment inks HP Z3200 shows none of these effects. Does that mean that this kind of metamerism is related to dye inks?

Wouldn't it be nice if Epson clarified what effect the media choices have on the printed image? Ha!

Again, thanks for your valuable, detailed and educated input.

 

[Ink stained Fingers]

you would need to do a spectral analysis of 'gray' patches under various light conditions, there are no simple answers, and the paper, the optical brightener can have an effect as well in lighter gray tones. And we don't know how HP mixes gray - it could be that they use more of the black ink and dither it , they may do more of 'under color removal - UCR'
https://en.wikipedia.org/wiki/Under_color_removal
Try as well the grayscale-B/W option.

 

[glasseye]

Greyscale-B/W option removes the metamerism, but also removes any colour toning (sepia, etc.) from the photo.
Greyscale print looks a little harsh - "chalky" might describe it best. I haven't tried it on other media. So many variables!

I have another L-805 question, but I'll make a separate thread for this.

Thanks again ISF.

 

[Ink stained Fingers]

When using the B/W option you could pre-treat your image adding a gradation curve to compensate that 'harshness' - or use a profile - you are in the middle of finding out the complexities to get a good B/W print, and please be aware you try to print B/W - or grayscale - with a color printer, that's not their prime purpose and that's the reason there was and is so much discussion in forums specifically around this subject

 

[glasseye]

... that's not their prime purpose ...

Indeed. The fact that it makes even just "acceptable" monochrome prints is a bonus.
The 805 is an excellent little printer. Just as enjoyable as its big bro, the Z3200.
FWIW, after two years, I see little fading or colour shifts with prints stuck scientifically to my fridge.

 

[MichaelKnight]

Thanks for your questions glasseye, under the thread I posted. If you can find a solution please comeback and write here please I am thinking about custom profiling(by a professional) but it would be a bit pricey I think, buying something like Colormunki for calibrating/custom profiling is of course much more expensive (currently I am saving money to buy a new smartphone in a few months).

 

[Ink stained Fingers]

Profiling can improve the neutrality of B/W prints and corrects non-linearities but does not fix the general problem , you need to adjust the color temp for the viewing condition as well for the profiling software , a profile does not fix the problem that profiled B/W prints may look different under different viewing light conditions, one profile is not correct for all situations. I would advise to adjust for daylight conditions since daylight is typically brighter than artificial light, and deviations are easier visible.

 

[MichaelKnight]

Thanks for your answer. Is changing the color temperature useful to get neutral grays on color pictures too or is it for B&W and we should use custom profiling to get neutral grays when printing color pictures (to optimize for viewing under daylight)?

 

[glasseye]

Profiles are used to ensure colour accuracy with a specific media and or inkset. Most of this discussion revolves around monochrome printing with dye inks. A good profile is what you need for "neutral grays when printing colour pictures"