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Neil
10-20-2003, 06:37 PM
Doing convert > grayscale still leaves color information in the colors, why is that?
Is there any way to convert your pallette to true 0,0,0,X ?

klingspor
10-20-2003, 07:39 PM
That's because it doesn't change the colour mode from RGB or CMYK... Mode > Grayscale on the other hand does.


edit: uhm wait... "Convert > Grayscale"? Where did you find that one?

Kotayus
10-20-2003, 08:16 PM
now im not 100% on this, but a black and white exposure is different than removing color. You can SIMULATE b&w, though you will never really capture the esscence of it in photoshop, im sure there are ways of adjusting brightness and contrast...though i think there will always be something about it that looks off.

sevenfingers
10-20-2003, 09:26 PM
If you don't want to get down and dirty with channels, the quickest way to get a decent B&W picture from a colour one, is to convert it to LAB mode, then remove the a and b channels.
You're then left with the lightness information in the picture, stripped from colour.

Kotayus
10-20-2003, 10:10 PM
thats a nice method!

Another that ive done it is: hit Ctrl+U and check the colorize box, remove all saturation.

Though the LAB method seems to make softer edges. I just tried it on a picture of me...and the lab method removed some of the freckles on my face.

Neil
10-21-2003, 12:24 AM
stefanminning: yes i meant Mode. Couldn't remember what the toolbar said exactly.

I tried the crtl+U and the colorize and both deem nice results, but both leave color values again. Cool techniques though :) Is this just the way PS is and how it always reports values?

See for the RGBs it's showing all 3 the same number (which is good), but for the CMYK rollover it shows 4 unique values when it should be 0,0,0,X.

Kotayus
10-21-2003, 01:03 AM
hey neil, did some searching...i didnt read all of the article but here ya go:

Clickeh (http://www.creativepro.com/story/feature/19449.html)

Seems like it might be on the right track

Kotayus
10-21-2003, 01:09 AM
well, i tried it out, im really hard pressed to say that i notice a difference, i like the lab mode (thanks sevenfingers!) i wasnt aware of it prior to this thread.

Though the channel mixing does seem to help too...maybe somewhere in between all of these lay the right mix?

Though in the article they state this:

"Printing Black-and-White Images::
Even if you've converted your image to Grayscale, you may not want to save it in Grayscale mode. If you're printing images on your home printer, you'll get better results by leaving your image in RGB or CMYK. This is because a grayscale image only triggers the black ink in a printer and you'll only get the 256 tones that are in the grayscale image. If you print a black and white image in RGB, all of your inks will print, and while your image may not be quite as neutral, you'll have a lot more richness in your printed tones than is possible with just one ink."

So this method keeps some RGB info intact...for print...that could be usefull...anyhow, thanks for starting the thread neil, this has been most helpfull.

dg
10-21-2003, 02:34 AM
Hi all,

You could:

Desaturate
Ctrl+Shift+U (But is not the same thing as a BW film)

RGB 2 Lab 2 Grayscale
Convert the RGB to Lab, select the L channel and go to Image > Grayscale, when it ask you about if you want Discard the Other Channel, hit yes.

RGB 2 Grayscale
Go to Image > Grayscale

Channel Mixer
Add a Channel Mixer ajustment layer, and set it to Monochrome and play with the values

Take a look at these exemples:

http://dgmedia.port5.com/tests/bw_test.jpg

For the Channel Mixer one I've used the following value:
R= +90
B= +16
G= +4
C= -2

I hope this helps,
See ya! 8)

Ikarus
10-21-2003, 03:00 AM
Diogo girondi you hit the nail right on the head, but you forgot one more.

CMYK mode copy to BLACK channel
In CMYK mode select your layer, "SELECT ALL"--> "COPY"--> Go to the channel's pallete and delete all the stuff in all your channels(C,M,Y,K) for that layer and -->"PASTE" into the BLACK channel.

Neil that's the only way your gonna get photoshop to sample the colors in the layer as 0,0,0,X. Although doing it like this creates a dull greyscale layer. You can always adjust the LEVELS, BRIGHTNESS, etc so that it won't be so dull. By the way what exactly are you going for, or trying to acomplish? Just curious.

klingspor
10-21-2003, 08:55 AM
Neil, could you explain again exactly what the problem is?

Because with all the methods mentioned in this thread, your result will be a gray scale image, which by definition does not include any colour values... well ok, it could include colour values, but as the R, G and B channels all have the same value, it appears a shade of gray.
If you want true b/w, you would convert it to a bitmap, which contains exactly two colours - in your case black and white. But according to your description, that isn't what you need, or is it?

If you're working with CMYK, it just might be an issue with its spectrum: CMYK includes only a fraction of the RGB spectrum's colours, so perhaps some colours on the gray scale are missing as well... but that I find quite unlikely. CMYK is generally used for print-design though, so if that's not what you're working on, be sure to switch to RGB!

halo
10-21-2003, 10:11 AM
if you convert from greyscale to CYMK then the "grey" will get spread across the 4 channels to provide the best colour match and density. To get just the K channel occupied, in greyscale selct all copy, convert to cymk, clear all the channels and paste it only onto the K channel.

Neil
10-21-2003, 04:58 PM
Originally posted by stefanminning
Neil, could you explain again exactly what the problem is?

Because with all the methods mentioned in this thread, your result will be a gray scale image, which by definition does not include any colour values... well ok, it could include colour values, but as the R, G and B channels all have the same value, it appears a shade of gray.
If you want true b/w, you would convert it to a bitmap, which contains exactly two colours - in your case black and white. But according to your description, that isn't what you need, or is it?



I treid the pasting in the K channel and there is still color values when you info the canvas or eye drop it.
I am doing print work, that's why i'm so interested in how PS deals with this. Yes, if it was screeen i'd do RGB.

Doing Bitmap will not give you gray values, i want the full spectrum from 0-100% of JUST K. If you do CONVERT it still prints always a little yellowish or a little bluish on a color printer. If i set it to print B/w then it prints much cleaner. I know technically that's all you should have to continue to do, but when you work with clients that are dumb, i don't want there to be any chances left for mistakes.

Maybe PS ALWAYS leaves values in the C, M, Y. But FYI, just because RGB are the same values, does not mean that the CMY are 0. You can have 0,0,0,X AND have the same RGB, just like you can have the same RGB and not the same x,x,x,x.

Neil
10-21-2003, 05:15 PM
Originally posted by Kotayus
...anyhow, thanks for starting the thread neil, this has been most helpfull.

Welcome! and thanks for contributing and helping out! Everyone has been very helpful and creative with their methods. I find it funny how there is always like 10 methods to doing anything in PS :)

halo
10-21-2003, 05:41 PM
neil, if you delete all the info in the CYM channels and paste into the K channel you wont have any data in the others....you have to paste into the channel itself not just paste as a layer. Photoshop will never spread pastes from one channel into another, that would defeat the point of channels, but you must make sure you are pasting only into the K channel and of course be working in CYMK colour mode.

Animosus
10-22-2003, 05:58 AM
Neil, I think what you are referring to is just a function of Photoshop that is always there. When you convert to Greyscale, the info pane shows you a simulated readout of the values in CMYK mode (which would be the values if you converted back into CMYK). If you want to see just a Greyscale readout, change the palette options and you should get a K% reading. If you change one of the readouts to "Actual colour", the sampling will always show you values of the colour space you are currently working in. Hope that helps

Neil
10-22-2003, 02:26 PM
halo: yeah, i made sure when i tried the second time, thanks.

Animosus: yeah, thats what i'm starting to think too. But then i guess i don't understand why.... even if it's just displaying it in CMYK mode without there actually being color there, then it could still display it as 0,0,0,X though.
Is there reasoning behind this?

Here is an example of what i mean:
http://web.ics.purdue.edu/~meskaunr/cmyk.jpg

halo
10-22-2003, 02:52 PM
hang on....i think i see the problem here

ok firstly the eyedropper will read out values of your colour mode and other colour modes, your still measuring whilst in greyscale, not cymk as i said.

You need to be working in cymk for my method to work, photoshop will always split the greyscale channel across cymk when it converts it to cymk, your eyedropper shows what these values will be.

to avoid this follow these steps exaclty

create your art in greyscale

flatten, select all, copy

convert to cymk

select all, fill with 100% pure white

the goto the K channel only, select all, paste, deselect.

Make sure your eyedropper is set to show the colour mode your are working in and measure then.


of course though if you wish to remain in greyscale then do so, as that will only print on the black channel, what the eyedropper shows you is what will happen if you convert....if you dont it wont....thats not to say that your printer wont convert it, but a good repro printer wont

Neil
10-22-2003, 05:23 PM
Halo: i followed your steps and it worked out. Thanks! But i dont' understand why being in 'grayscale' is not grayscale. It only works if you flatten and redo CMYK converting.

BUT...

It shows in the info pallette that you have 0,0,0, X% BUT when you eyedrop it, the color being picked up is still composed of all 4 CMYK AGAIN. Is that like that on your end too, or did i miss a step again?

halo
10-22-2003, 07:57 PM
i think your misreading your eyedropper, heres why

in your palette options you can set or should perhaps set it to the following

First colour read out set to "actual"

Second set to "CYMK"

Now we have that, this is what you should see.

In greyscale on the left of the eyedropper info palette you will see a single "K" with a number, on the right you will see CYMK with numbers in each channel. Now what this means is you are in greyscale, your image is just made up of black, but the values on the right show what your image will be made up from when you convert to CYMK.

Now if you convert and do the steps i descibed above, your eyedropper will change to CYMK on the left but show values only in the black channel, but also the CYMK on the right should show the exact the same channels, but you do need to be in CYMK to do this. If it doesnt then either your eye dropper is showing something else (ie its not setup logically) or you missed a step or i have missed something. Essentially your removing all the data and just dropping greyscale info just into the black channel (make sure thats the only one selected in your channels list in CYMK).

it should look like my attachment :)

Animosus
10-23-2003, 12:22 AM
Originally posted by Neil
even if it's just displaying it in CMYK mode without there actually being color there, then it could still display it as 0,0,0,X though.
Is there reasoning behind this?

There is a reason behind this. When you are in Greyscale mode, your actual colour is in values of black (K). Photoshop is simulating values for the same area in CMYK. These are not ACTUAL VALUES while you are in Greyscale mode, but are an indication of what the black (K) value will be translated into when photoshop splits one channel into four (CMYK). Why does photoshop do this? Because it needs to split the information into four channels, sharing the information over these channels in CMYK mode to give the richest blacks.

Is this getting to the heart of your question, or have I missed the mark?

Neil
10-24-2003, 09:04 PM
For some reason i can't load Cgtalk at home anymore. The page always errors when it comes up... Sooooo.... i haven't been able to try recent suggestions.
I will as soon as i "fix the glitch".

allenatl
10-28-2003, 09:54 PM
No need to worry. Your grayscale image is in only black and white. As several have stated in earlier posts, the CMYK values are only showing you what the values would be if converted back into CMYK. The reason for this is because when printers print CMYK, a combination of CMYK is used to get what is called a rich black. Without the mixure of colors the black would look dull and flat on the final prints. Since Photoshop's main market over the years has been the print and graphics industry, most of its default settings are designed to accomodate work in that field. (With web, 3d, etc. that's probably changing or will change.)The settings are adjustable in the Color Settings in the Edit menu but it's only if you are comfortable doing color correction work. Bottom line is that the
CMYK numbers are only there as a reference for printers. If your image is in grayscale mode, then it contains only black and white info.

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