Question about basic editing - DPChallenge Forums

04/05/2005 09:51:24 PM · #1

I just want to make sure on this.

If I take an image, convert from RGB to CMYK, seperate the Black channel and only work with that channel, using levels and curves, it that okay?

Just want to make double sure, can't get the effect I want with the other channels and legal editing in Basic.

Deannda
Thanks

Canon EF 24-105mm f/4.0L IS

04/05/2005 10:35:58 PM · #2

45 minutes, 4 council members on line and no answer?

Deannda
Hellllllllllllllloooooooooooooo??????

scalvert

Canon EOS-5D Mark III

04/05/2005 11:30:47 PM · #3

Sounds OK to me. Try emailing a few SC members directly.

04/05/2005 11:32:29 PM · #4

Thanks, think I will do that since they aren't listening right now, *sniff, sniff, sniff*

Deannda
Darn cold! ;)

04/06/2005 01:47:39 AM · #5

Interesting question, I'm not sure if I understand exactly what you're asking. It seems to me you are talking about making a new layer that contains ONLY black-channel information, and then applying levels and curves to that layer separate from the others, and I don't think you can do that. You're not allowed to have any layers that contain pixels in basic editing. But I may have misunderstood what you're proposing.

Robt.

timj351

Sony DSC-F707

04/06/2005 02:05:09 AM · #6

It seems legal to me as long as you are not working on extra layers and you are just working on the particular color channel in levels or curves.

T

Canon EF-S 18-55mm f/3.5-5.6

04/06/2005 02:11:50 AM · #7

Right, Tim, if that's what's being proposed. It's unclear to me. I'm left with the idea that maybe neuf wants to separate out the black channel and use only that channel, which would involve a new layer with pixel information... Maybe I'm confused, wouldn't be the first time... But I'm not sure you actually CAN open up a CMYK channel and then apply levels and curves to it wiuthout first copying the channel to a new layer.

Robt.

addendum; the only way I can find to do this is to load the channel as a selection and then use curves and levels on the selection. Does anyone know a way to apply curves and levels to only one of the channels WITHOUT making a selection? I'm not that familiar with channels, and i find them very interesting.

Message edited by author 2005-04-06 02:26:22.

fulgent

Canon EOS-20D

04/06/2005 02:56:08 AM · #8

Conversion to B&W is acceptable in Basic Editing.

Conversion to Black & White can be done in various ways without making a new layer.

You can go to the CMYK Black channel, select it and change the mode to Grey Scale and allow the deletion of the unused channels.

You can also change the mode to Lab Color and just use the "Lightness" channel and convert it's mode to Grey Scale and delete the other channels.

And desaturation of the colors.

It may be questionable if you then change the image mode from Grey Scale back to RGB, new layers are added. So this would be interesting to get a ruling on this step.

Canon EF 24-105mm f/4.0L IS

04/06/2005 03:30:08 AM · #9

I'm assuming the OP wants to keep the image in color, but wants to do levels and curves on the black channel only. And I can't find any way to do it without cloning the black channel out to a new layer. So my personal question is, does anyone know if this is possible? For my own information, even if it's not what is being proposed here.

If what she's asking is, can she DISCARD the other channels and just use the black channel in creating a B/W image, that's another question altogether. It would seem to be completely legal, to me.

Robt.

bmatt17

Canon EOS-600D/T3i Rebel

04/06/2005 03:51:26 AM · #10

If the conversion to CMYK is legal, then can't you just run levels and curves, and work on only the black channel?

04/06/2005 04:18:27 AM · #11

Originally posted by bmatt17:

If the conversion to CMYK is legal, then can't you just run levels and curves, and work on only the black channel?

Not that I can figure out. To get to an individual channel you have to work out of either channel mixer, which is an adjustment, and you can't run an adjustment on an adjustment basically, or work out of the channels pallette, where in order to apply an adjustment to an individual channel you have to make a selection out of it, which is illegal in basic but fine ina dvanced.. Of course, you can ELIMINATE all the channels but the black channel, and go from there, that would seem to be legal. But I can't find a way to do levels or curves on an individual channel without making a layer out of it first. There may be a way to do this, but I can't find it, and I love to have it in my arsenal if it exists.

Robt.

Canon EF-S 18-55mm f/3.5-5.6

04/06/2005 05:44:24 AM · #12

Originally posted by bear_music:

.

If what she's asking is, can she DISCARD the other channels and just use the black channel in creating a B/W image, that's another question altogether. It would seem to be completely legal, to me.

Robt.

That is my question. Thanks!

Deannda
Not that I'll have to prove anything anyway, below a 5 right now, ah well, such is life

fulgent

Canon EOS-20D

04/07/2005 03:54:28 AM · #13

Originally posted by bear_music:

But I can't find a way to do levels or curves on an individual channel without making a layer out of it first. There may be a way to do this, but I can't find it, and I love to have it in my arsenal if it exists.

Robt.

To adjust levels on a single channel without using the selection tool or creating a new layer try this:

You open the channel menu and click on the channel you want to adjust.

The composite image and other channels should turn off the "eye" icon. The "eye" icon should only appear in the channel you picked.

When only one channel is highlighted the image will be a black & white representation of the tone values for that color. (Click on another channel and the black & white values also change.)

Now you can go to the Image/Adjustments menu and see what options you can apply to that channel.

Have fun!

GeneralE

Canon PowerShot S3 IS

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

04/07/2005 04:07:53 AM · #14

Originally posted by fulgent:

Originally posted by bear_music:

But I can't find a way to do levels or curves on an individual channel without making a layer out of it first. There may be a way to do this, but I can't find it, and I love to have it in my arsenal if it exists.

Robt.

... When only one channel is highlighted the image will be a black & white representation of the tone values for that color.

Now you can go to the Image/Adjustments menu and see what options you can apply to that channel.

You can apply effects from the Adjustments Menu to individual channels as described here, but what you can't do is save that in an Adjustment Layer for later modification -- as soon as you create the Adjustment Layer, all color channels become active again.

Some of my better B&W "conversions" lately have merely been copying the Green Channel into a new Grayscale document, adjusting, and converting back to RGB.

Message edited by author 2005-04-07 04:08:35.