Images converted to grayscale look purple

snailface

Hi, a while back I posted about a problem I was having with my grays having a purple hue. Thanks both to OYBRO and cbadland for the help.

Now I have a new but related issue. When I convert an image from RGB to grayscale, the grayscale is more like a purple scale. To top it off, if I use the eyedropper to choose a color from the now purple image, it recognizes it as having a purple hue.

Anyone have any ideas. I'm at my wits end. I'm working on a project right now where I need to convert a photo to grayscale for a client, and this purple mush just isn't acceptable.

Here's an example.

cbadland · Posted: Sat Jul 23, 2005 5:53 pm Post subject:

The Photoshopeyedropper info palette NUMBERS show a color-cast?(Convert to Grayscale then set the Info Palette read-out to show RGB. Or convert to Grayscale then convert back to RGB and look at the RGB numbers in the info palette. RGB numbers should all be the same).

Yeow.

Try:
Resetting your color setting to North American General Purpose before converting.
Recalibrate your monitor profile or download a new one.
And
Post your converted B/W image (not a screen-shot) so we can see how it looks.

Gallo_Pinto · Posted: Sat Jul 23, 2005 6:08 pm Post subject:

you're using image > mode > greyscale? just wantred to be clear if you're doing it that way.

There are other ways of effectively converting an image to greyscale. You could use image > adjustments > hue/saturation, and just drag saturation all the way down. Obviously this mon't actually put the image in greyscale mode, and you'll have a larger file size than if it's actually in greyscale mode.

This last method of converting to greyscale is my personal favourite:
with the image in RGB moe, hide two of the RGB channels. depending on what colours predominate on the image, you'll get a different efect if you hide different stuff. try view each one individually and see which looks best. Theh delete the channels yo're not using. Then when you convert to greyscale, the one remaining channel (which will now have become a C,M,Y, or K channel willl become your one grey channel. With any luck it won't gain purple when you convert.

Just out of curiosity,m after you'd converted your posted image and it looked purple, what did the channels pallette show?

i must say, that's one of the strangest photoshop problems I've ever heard of. Just to get that one image converted, you could email it to someone and have them just convert it and send it back.
(if you think it's worth a shot, i'm travis.rempel@gmail.com)

snailface · Posted: Sat Jul 23, 2005 7:25 pm Post subject:

The images I posted above were taken right after recalibrating my monitor.

I don't think its a monitor calibration issue, becuse when working in RGB, my grays are just fine, its when I use image>mode>grayscale that the problem occurs.

And thanks for the tips on other ways to convert, I don't know why i didn't think of that.

As for what the channels contain after the conversion, they are just what you'd expect for a NORMAL conversion, but the combined RGB channel has a purple hue.

It's just so damn frustrating.

Gallo_Pinto · Posted: Sat Jul 23, 2005 8:40 pm Post subject:

obviously not a monitor calibration problem, because it looks purple to me too.

Back to channels, after chsnging mode > greyscale there should only be one channel, it should be called "grey". if you have an RGB channel still, delete it.

I might be tempted to try re-installing photoshop.

snailface · Posted: Sat Jul 23, 2005 9:42 pm Post subject:

My apologies.

I do indeed only have one channel after converting to greyscale, and it is titled "Gray" and it is purplish.

The channels I was looking at before were the channels that resulted from me converting to grayscale, and then back to RGB.

Gallo_Pinto · Posted: Sat Jul 23, 2005 9:51 pm Post subject:

other than "Dude, that's wierd", I don't know what to say.
Re-install or get someone to convert it for you just to get your deadline.

stevealmighty · Posted: Sat Jul 23, 2005 11:50 pm Post subject:

Try taking your original image, converting it to lab color (image>mode>lab color), then select your "lightness" channell, then convert your image to grayscale (image>mode>grayscale). From here you can convert you image back to your working or printing mode (either RGB or CMYK). Adjust your levels and/or your brightness & contrast to fine tune your image. When I print black and white photos, I use this method, as I feel I get better results.

cbadland · Posted: Sun Jul 24, 2005 7:29 am Post subject:

Did you use Adobe Gamma? Did you start with a non-hosed profile?
Are you using a normal default Color Setting like US Prepress or North American General purpose?
Can you give an example of the RGB numbers of a mid-gray area of your Grayscale file?
And try trashing your PS preferences. (hold down Shift+Alt+Ctrl as you launch the program, you’ll be prompted to reset your prefs.)

AND...
What is your video card and driver version?
There have been some conflicts causing problems with Adobe Gamma.

swanseamale47 · Posted: Mon Jul 25, 2005 12:24 pm Post subject:

I saw this problem somewhere else and the answer was in the adobe colour settings.

Heres what was said there

You've got bad color settings, make sure that you have not saved the results of adobe gamma to the sRGB profile.

Re-run Adobe Gamma , but make sure to follow the instructions given at: http://computer-darkroom.com/ps8_colour/ps8_1.htm

hope this helps Wayne

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