Greyscale in sRGB vs Grey Gamma 2.2

[Erland]

Good Evening!
Ok, so another, perhaps obvious to some, question. But why is that the sRGB greyscale image with either a black and white adjustment, or a black to white gradient overlay show a slight slight color tint in the lighter shadows, when the exakt same image, print settings (PS, Perceptual, my own profile) converted to Grey Gamma 2.2 is more neutral. It is only slight, but obvious even when they aren't displayed next to each other?
The same is for Relative Colorimetric.

Kind regards!

[digitaldog]

The gamma settings are not the same (sRGB doesn't really have a gamma curve, it's a Tone Response Curve or TRC, it doesn't follow the Gamma formula). But that's not the issue with the slight color cast. I just read someone say they saw a similar issue and it turned out to be an issue with GPU (what else is new?). Try turning it off, any better?

[mouse]

My question (not rhetorical) is: If one wishes to produce a B&W print, why not routinely convert to Grey Gamma 2.2 prior to output to the printer?  That has always been my practice; am I missing something?

[digitaldog]

My question (not rhetorical) is: If one wishes to produce a B&W print, why not routinely convert to Grey Gamma 2.2 prior to output to the printer?  That has always been my practice; am I missing something?

What printer?
Depends on the printer but few would be served by sending them a grayscale document.

[Erland]

Will try it tomorrow. I often want to tint my black and white slightly warm, just to make it match my Darkroom prints hanging on the same wall, and can't use gray Gamma 2.2 every time.

[mouse]

I wrote:

My question (not rhetorical) is: If one wishes to produce a B&W print, why not routinely convert to Grey Gamma 2.2 prior to output to the printer?  That has always been my practice; am I missing something?

What printer?
Depends on the printer but few would be served by sending them a grayscale document.

Let me elaborate on my question; and I hope I am not hijacking this thread.

As for the printer, I do not print in-house.  I send most to Costco.
My B&W images are of two origins: B&W film scanned in Nikon 4000 and digital images converted to B&W in software.

For the scanned negatives the scanner is set to 'negative B&W' which outputs a tiff file in Grey gamma 2.2.  This file is edited in PS before sending to the printer; color space unchanged.  I could convert to an RGB color space before sending to the printer.  Would this make a difference?  

For the digital images, what is the recommended workflow to produce a B&W image to be sent to the printer?  Usually I make the conversion in ACR (Convert to greyscale which results in an image in Grey Gamma 2.2) and do any further editing (if needed) in PS.

[digitaldog]

As for the printer, I do not print in-house.  I send most to Costco.
My B&W images are of two origins: B&W film scanned in Nikon 4000 and digital images converted to B&W in software.
For the scanned negatives the scanner is set to 'negative B&W' which outputs a tiff file in Grey gamma 2.2.  This file is edited in PS before sending to the printer; color space unchanged.  I could convert to an RGB color space before sending to the printer.  Would this make a difference?

Ask Costco but I suspect you want to send them RGB data, perhaps in a working space such as sRGB where R=G=B is a known neutral.

[mouse]

Andrew,
Thanks.

[Erland]

Ask Costco but I suspect you want to send them RGB data, perhaps in a working space such as sRGB where R=G=B is a known neutral.

Are not R=G=B neutral in some other colorspaces? Thinking if my printer profiles are one of those then..

I know that sRGB has a TRC instead of a gamma curve. however converting from sRGB to grey gamma doesn't produce any visual difference on my monitor, but it does when printing it.

[Erland]

I opened an image in Photoshop, black and white, in sRGB, and converted it to gray gamma 2.2, saved it as a copy, and opened them side by side in PS, and applied my printer profile as a soft proof, both in Perceptual. Both looked identical. So why is it that my printer prints them differently, if the profile should make them appear the same? Something wrong with my workflow?

[digitaldog]

I opened an image in Photoshop, black and white, in sRGB, and converted it to gray gamma 2.2, saved it as a copy, and opened them side by side in PS, and applied my printer profile as a soft proof, both in Perceptual. Both looked identical. So why is it that my printer prints them differently, if the profile should make them appear the same? Something wrong with my workflow?

It's not about looking the same, it's about the numbers. Are they identical?

[Erland]

Yes Andrew. However I Measure, using either soft proof or convert to my profile from sRGB and gray gamma, i get the identical numbers. Both in RGB and in LAB.

[eliedinur]

The 1400, which has only a single black ink cartridge instead of two blacks - black and light black - or like the 3880, three blacks - black, light black and light, light black - is probably not capable of producing a perfectly neutral B&W print when sent an RGB file, no matter how good the soft proof looks.

R=G=B is grey in a matrix based RGB working space by design, but it is not necessarily the case in a device space, at least not throughout the range from black to white.

[digitaldog]

Yes Andrew. However I Measure, using either soft proof or convert to my profile from sRGB and gray gamma, i get the identical numbers. Both in RGB and in LAB.

Are the numbers identical after conversion to your printer profile? I would suspect not. And if so, that's why there's a difference. At least if I'm following all this (I'm not sure  )

[Erland]

Actually, you are right! I was looking at LAB values, but they are the same, but not the RGB numbers. Strange!
I would be more cheerful if it was sRGB who had the most neutral prints instead, so I could tint it slightly.

Thanks for the help friends!

[digitaldog]

I would be more cheerful if it was sRGB who had the most neutral prints instead, so I could tint it slightly.

But you can tint it, it's RGB. You can't tint the grayscale. The reason sRGB isn't neutral on output has nothing to do with sRGB per se, it's always neutral like all RGB working space when R=G=B. It's the output profile that's introducing the color cast.

[Erland]

Hm.. So why isn't sRGB with R=B=G values all through converting the same into my printer colorspace as going to gray gamma first and then my printer profile? Does it have something to do with the TRC.

[BobShaw]

I don't think that you can expect great results using a budget printer. You get what you pay for usually.