Green cast on my monochrom prints… what am I doing wrong?

[Olaf_ZG]

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I don’t print myself, and don’t have the place to setup a nice printing station. Instead, I send jpegs to my local photoshop who prints them on canon (i think).

Colourprints come out great, the monochrom always have a green cast. Today I received prints back, one monochrom (m10m) and one b/w converted (lrc) from the sl2.

both photos where edited in Lrc, from dng file and then exported as jpeg for printing. Same preset for export.

the b/w converted was really b/w, the monochrom had a strong greencast. On screen, both look b/w, no colourcast.

what could be the cause/reason? Thanks.

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[pippy]

32 minutes ago, Olaf_ZG said:

I don’t print myself, and don’t have the place to setup a nice printing station. Instead, I send jpegs to my local photoshop who prints them on canon (i think).

Colourprints come out great, the monochrom always have a green cast. Today I received prints back, one monochrom (m10m) and one b/w converted (lrc) from the sl2.

both photos where edited in Lrc, from dng file and then exported as jpeg for printing. Same preset for export.

the b/w converted was really b/w, the monochrom had a strong greencast. On screen, both look b/w, no colourcast.

what could be the cause/reason? Thanks.

This is just a long shot - so please bear with me - but are you converting your DNG files from your Monochrom to Greyscale before you hand them over for printing?

Here is a triptych of three images from the same file. The one on the left is as-imported as a JPEG from the DNG. The one in the middle is what I can get (saturation has been exaggerated for the purposes of the post) when this original JPEG is going to be adjusted for 'Levels' in Photoshop. The right-hand image is what I get when I convert either of these previous two JPEGs as 'Greyscale';

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I have absolutely no idea of the ACTUAL technicalities behind the engineering but from my experience with my M Monochrom and using Ps although a Monochrom (alledgedly) captures files 'in black and white' the imported DNG file does contain RGB information. It is only when the imported file is converted to Greyscale that the tones are colour-neutral.

I do also have the option to reduce saturation of the original DNG file to 0% in the RAW Converter dialog-box before processing-out but, just occasionally, I quite like to have the option to reproduce a Monochrom image almost as if it were a Duotone Photograph...

😺

I could well be miles off(!) but I just thought I'd put this out as a possibility...

Philip.

[Olaf_ZG]

@pippythanks. Will try a set of images. Did not expect I would need to convert to greyscale, but looking at your example, it might be needed. Question then is, when to convert: at the beginning or at the end.

maybe @jaapvor @Jeff S can jump in as both use mm’s and are doing prints as well.

[jaapv]

57 minutes ago, pippy said:

This is just a long shot - so please bear with me - but are you converting your DNG files from your Monochrom to Greyscale before you hand them over for printing?

Here is a triptych of three images from the same file. The one on the left is as-imported as a JPEG from the DNG. The one in the middle is what I can get (saturation has been exaggerated for the purposes of the post) when this original JPEG is going to be adjusted for 'Levels' in Photoshop. The right-hand image is what I get when I convert either of these previous two JPEGs as 'Greyscale';

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

I have absolutely no idea of the ACTUAL technicalities behind the engineering but from my experience with my M Monochrom and using Ps although a Monochrom (alledgedly) captures files 'in black and white' the imported DNG file does contain RGB information. It is only when the imported file is converted to Greyscale that the tones are colour-neutral.

I do also have the option to reduce saturation of the original DNG file to 0% in the RAW Converter dialog-box before processing-out but, just occasionally, I quite like to have the option to reproduce a Monochrom image almost as if it were a Duotone Photograph...

😺

I could well be miles off(!) but I just thought I'd put this out as a possibility...

Philip.

No, the DNG file does not contain colour information, but if converted ( or exported as in LR) as an RGB file it is divided up over three equal colour channels which is quite useful if you want to do toning. The balance between the three channels is altered in that case. So basically your middle image is a toned B&W file. The only way to ensure a neutral B&W file is to work in greyscale. I normally work in RGB as I like to add a bit of sepia or cyan depending on the subject. 
if you use a printer that is not designed for B&W, lacks grey ink for instance, some ink/paper combinations will exhibit metamerism, manifesting itself as a coloured sheen in  some light conditions and at certain angles. Jeff can fill you in on using RIPs and specialized ink. 

[jaapv]

This is basically something that you should discuss with your printshop and establish exactly how the files should be delivered to get consistent results. 

[Jeff S]

20 minutes ago, jaapv said:

This is basically something that you should discuss with your printshop and establish exactly how the files should be delivered to get consistent results. 

This.  If not clear and successful, change shop.

Jeff

Edited June 6, 2024 by Jeff S

[pippy]

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3 hours ago, jaapv said:

No, the DNG file does not contain colour information, but if converted...as an RGB file it is divided up over three equal colour channels which is quite useful if you want to do toning...The only way to ensure a neutral B&W file is to work in greyscale. I normally work in RGB as I like to add a bit of sepia or cyan depending on the subject....

If you use a printer that is not designed for B&W, lacks grey ink for instance, some ink/paper combinations will exhibit metamerism...

Thanks for that post, Jaap, which explains much which I've seen but not understood completely.

It sort-of confirms my assumptions and explains much which I assumed to be the case but without any confirmation as to "Why?"....

My own printer has a 6-resevoir ink set-up which includes a dedicated Grey cartridge as well as the standard CMYK but, in addition, features a supplementary 2x capacity Black cartridge due to the likelihood of the printer being used to output Monochrome prints.

Philip.

Edited June 7, 2024 by pippy

[adan]

I print RGB-monochrome images all the time, with no color tints. They never ever ever need "conversion to grayscale" to print correctly.

But I do that myself, with a printer that knows how to print a "color" that is 128R/128G/128B (a neutral gray) as a - ta-da - neutral gray. (Epson 900).

It is far more likely that the outside lab simply does not have a correct workflow for printing monochrome images the right way - I have definitely seen labs produce green (usually) "B&W" pictures - becasue they simply don't know how to tune their printer for digital files.

Other labs, of course, figured out how to do this 20+ years ago. 😉

May depend also on whether the lab prints are still chemical, or if they have switched over to inkjet - and which inkjet.

Jaapv has the right answer - check with the photo shop that produced the tint, and ask them how they can stop doing that.

[Olaf_ZG]

Thanks all. According the shop, according to them, all settings were correct. So I might need to find a printer, or do it myself, which I am not aiming for due to lack of space.

Strange though, that the b/w from the sl2 was real b/w without green cast.

[Jeff S]

Find another shop; doesn’t need to be local. 

If you don’t require huge prints, a 13 or 17 inch printer will fit easily on an office desktop, or can be operated remotely from a different home location via Ethernet, etc.  Then nobody to blame but yourself (but I think you’d be fine, with proper B&W prints).

Jeff

[jaapv]

15 hours ago, Olaf_ZG said:

Thanks all. According the shop, according to them, all settings were correct. So I might need to find a printer, or do it myself, which I am not aiming for due to lack of space.

Strange though, that the b/w from the sl2 was real b/w without green cast.

"All settings were correct" 🙄  The hardest thing in printing is to get it from your screen into the printer to produce the same (well, similar)  impression on paper. They should have sat down with you, run a test print from your file and if it turned green again, analyzed why.  Just giving a defensive answer is not acceptable.

[Ko.Fe.]

I always got non BW from the labs if they were just a lab. For BW prints I was going to real mom and dad shop where they had person who knew about printing.

And I never bothered with Canon for printers. Epsons have option for bw print in the print settings. But again, someone in the lab has to enable it. 

[adan]

Bottom line - black or gray inks use carbon-black as their pigment. Essentially high-grade, finely-processed soot.

It can have a faint green cast. Not enough to notice with color images, where the "real" color inks are also used and overpower its tint - but with a monochrome image (either from a Monochrom Leica, or converted from any other camera, or from B&W film scans), the tint is more obvious, if it is the only pigment used.(**)

I used to get green overall tints in B&W images using a 4-ink Epson (or maybe it was a Canon/Apple) - 18-20 years ago.

Once I got a more up-to-date Epson (800 series and later, 8-9 inks MKKKCCMMY) - Epson's driver algorithms would add just a hint of the lighter-magenta ink to "B&W" prints, to counteract the native faint green of the "black" inks exactly.

________
** side note on perception of faint color tints. I went to a photo workshop in 1999, where a Kodak tech person was one of the presenters. Someone asked him if Kodak could produce an E6 "monochrome" Ektachrome (to compete with the likes of Agfa Scala, Ilford XP2 and Kodak's own BW400 CN).

He said NO - E6 chemical dye creation in the processing (not in the factory) was not perfect enough to get a perfectly consistent "gray" from roll to roll. Color processing deviations of ~1% are imperceptible in a full-color image - but in a pure-grays image, they stick out like a sore thumb. Especially if mixing slides, in a presentation, that have been run through many different labs over many different years. They would clearly have all kinds of different faint tints (brown, blue, green, magenta, etc.)

Could not compete with reversed-silver images like Scala - or C41 negatives like XP or BWCN, when darkroom-printed on analog B&W silver paper (back then, digital printing was for office memos 😉 ).

Edited June 7, 2024 by adan

[JimP]

Interesting thread, I purchased one of the new Epson Eco Tank printers (8550). I printed a monochrom image in photoshop and converted to jpeg just before sending to the printer (it does not accept greyscale). I got the dreaded green tint in the print. I tried profiling the printer which improved things, but still green. I then printed using Advanced Black and White and it solved the problem. I never had that issue on the 3880. 
 

by the way, the 8550 is a very good printer. I use it to print 4x6 and 5x7. If I print to hang on the wall, I use the 3880.