chanel mixer problem

try displaying just the channel you want …
then "select all" and copy ….
Make a new window and paste ….
(Keyboard short cuts are F3 and F4 respectively)
Timmy
"marko" wrote in message

hi.
i have a problem when turning pics to black and white.when i use chanel mixer with monochrome option and this setings: red 100% green 0% and blue 0% I dont get the same result like when i click the red chanel in the chanels palette.same problem is with blue and green chanel.does anyone know why is that?
thanks

"marko" wrote in message

hi.
i have a problem when turning pics to black and white.when i use chanel mixer with monochrome option and this setings: red 100% green 0% and blue 0% I dont get the same result like when i click the red chanel in the chanels palette.same problem is with blue and green chanel.does anyone know why is that?
thanks

Interesting. I get exactly the same result as long as I don’t convert the monochrome image from RGB to Grayscale. But that conversion introduces some slight differences. I see nothing in the help to explain this.

Interesting. I get exactly the same result as long as I don’t convert the monochrome image from RGB to Grayscale. But that conversion introduces some slight differences. I see nothing in the help to explain this.

thats what wories me …i should get the same results but i dont

Interesting. I get exactly the same result as long as I don’t convert the monochrome image from RGB to Grayscale. But that conversion introduces some slight differences.

If you open your Info palette, you will find that it doesn’t. The file is exactly identical, pixel for pixel, before and after the conversion.

It *looks different* on your screen, because Photoshop does color management for grayscale images but not for multichannel images. (If you don’t understand what that means, read the chapter on color management in your manual.)

It has a different appearance on your monitor after the conversion, but it is not actually different at all. If you disable color management for grayscale images, it will look the same on your monitor before and after the conversion.

—
Rude T-shirts for a rude age: http://www.villaintees.com Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

In article ,
(Tacit) wrote:

Interesting. I get exactly the same result as long as I don’t convert the monochrome image from RGB to Grayscale. But that conversion introduces some slight differences.

If you open your Info palette, you will find that it doesn’t. The file is exactly identical, pixel for pixel, before and after the conversion.
It *looks different* on your screen, because Photoshop does color management for grayscale images but not for multichannel images. (If you don’t understand what that means, read the chapter on color management in your manual.)
It has a different appearance on your monitor after the conversion, but it is not actually different at all. If you disable color management for grayscale images, it will look the same on your monitor before and after the conversion.

You be da man, Tacit! Thanks for that.

In article ,
(Tacit) writes:

Interesting. I get exactly the same result as long as I don’t convert the monochrome image from RGB to Grayscale. But that conversion introduces some slight differences.

If you open your Info palette, you will find that it doesn’t. The file is exactly identical, pixel for pixel, before and after the conversion.

No, it is not. I used Apply Image to find the difference between the two images, and the histogram of the differences was not all zero. Auto Contrast on the difference revealed systematic deviations from zero.

—

Warren S. Sarle SAS Institute Inc. The opinions expressed here SAS Campus Drive are mine and not necessarily
(919) 677-8000 Cary, NC 27513, USA those of SAS Institute.

"Warren Sarle" wrote in message

In article ,
(Tacit) writes:

Interesting. I get exactly the same result as long as I don’t convert the monochrome image from RGB to Grayscale. But that conversion introduces some slight differences.

If you open your Info palette, you will find that it doesn’t. The file

is

exactly identical, pixel for pixel, before and after the conversion.

No, it is not. I used Apply Image to find the difference between the two images, and the histogram of the differences was not all zero. Auto Contrast on the difference revealed systematic deviations from zero.

Was the Gamma for Grayscale and RGB the same?

Bart

In article <buhko6$2ld$ (Warren
Sarle) wrote:

In article ,
(Tacit) writes:

Interesting. I get exactly the same result as long as I don’t convert the monochrome image from RGB to Grayscale. But that conversion introduces some slight differences.

If you open your Info palette, you will find that it doesn’t. The file is exactly identical, pixel for pixel, before and after the conversion.

No, it is not. I used Apply Image to find the difference between the two images, and the histogram of the differences was not all zero. Auto Contrast on the difference revealed systematic deviations from zero.

Maybe we had best have the exact description of steps. Is someone using mode to change to grayscale at the end? That function applies a given sample of colors, correct?

No, it is not. I used Apply Image to find the difference between the two images, and the histogram of the differences was not all zero. Auto Contrast on the difference revealed systematic deviations from zero.

What two images are you comparing–the image before the conversion from Multichannel to grayscale, or the original channel in the RGB image to the grayscale image?

—
Rude T-shirts for a rude age: http://www.villaintees.com Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

"jjs" wrote in message

In article <buhko6$2ld$ (Warren
Sarle) wrote:

In article ,
(Tacit) writes:

Interesting. I get exactly the same result as long as I don’t convert the monochrome image from RGB to Grayscale. But that conversion introduces some slight differences.

If you open your Info palette, you will find that it doesn’t. The file

is

exactly identical, pixel for pixel, before and after the conversion.

No, it is not. I used Apply Image to find the difference between the two images, and the histogram of the differences was not all zero. Auto Contrast on the difference revealed systematic deviations from

zero.

Maybe we had best have the exact description of steps. Is someone using mode to change to grayscale at the end? That function applies a given sample of colors, correct?

1. Open an RGB image. I’m using Adobe RGB (1998) color space.
2. Image>Adjustments>Channel Mixer. Check the Monochrome box.
this makes all three channels identical. Call this image Mono;
e.g., http://home.nc.rr.com/sarle/Mono.tif
3. Image>Duplicate. Call it Gray.
4. Image>Mode>Grayscale
http://home.nc.rr.com/sarle/Gray.tif
Since all three channels are the same, it should make no difference how they are weighted. Gamma is 2.2, which I think is the same as Adobe RGB.
5. Image>Apply Image. Mono is the source. Pick any channel since they’re all the same. Gray is the target. Blending mode is Difference. I’m sure Tacit can spot the differences instantaneously. http://home.nc.rr.com/sarle/Diff.tif
6. For those lacking Tacit’s keen vision, use Image>Histogram or Image>Adjustments>Auto Contrast
http://home.nc.rr.com/sarle/Auto.tif

I had done this earlier on a 4 megapixel version of this image and the effect was much more dramatic. When I reduced it to a height of 400 pixels, the difference was exactly zero.

2. Image>Adjustments>Channel Mixer. Check the Monochrome box.
this makes all three channels identical. Call this image Mono;
e.g., http://home.nc.rr.com/sarle/Mono.tif

At this point, the image is still RGB, and will be treated as RGB for the purposes of color management.

3. Image>Duplicate. Call it Gray.
4. Image>Mode>Grayscale
http://home.nc.rr.com/sarle/Gray.tif
Since all three channels are the same, it should make no difference how they are weighted. Gamma is 2.2, which I think is the same as Adobe RGB.

The conversion to grayscale, and the color management settings for grayscale images, are probably what’s causing the difference here.

If the RGB->grayscale conversion simply averaged the values in the red, green, and blue channels, then the RGB version and grayscale version would be the same, since all three channels in the RGB version are the same. However, that’s not what happens. What’s actually happening is you have two different color spaces, one for the RGB version of the image and one for the grayscale version of the image, and when you compare the grayscale version with the RGB version, they won’t be the same.

If you converted the RGB version of the image to Multichannel mode, then took one of those three channels in the Multichannel image and converted it to grayscale, the grayscale version should be identical to the channel in the Multichannel image (which is what I thought you were doing). But converting an RGB image whose channels are all identical to a Grayscale image won’t give you the results you expect.

I’d say either split the channels in the RGB version or convert the RGB version to multichannel, then take one of those channels and convert it to grayscale. The grayscale version should be the same as the individual channels in the RGB version.

—
Rude T-shirts for a rude age: http://www.villaintees.com Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html