I am retouching a color photo with a badly damaged blue channel. I trying to grasp the ins and outs of both Apply image and Calculations. Can anybody suggest a good source text or video on these subjects?

Thanks
Dave Bliss

Katrin Eismann's Photoshop restoration and retouching has an little section on pg 131 (2nd ed) and it goes over how Chris color corrects with Apply image. Maybe Chris himself (aka Cricket) can give a little more insight on both these tools as I hear he is great with both of them.

*Edit*
Heres some tutorials I found...thanks for bringing up the subject or I wouldn't have found them!

http://www.creativepro.com/story/feature/8126.html

http://www.ledet.com/margulis/Poetry.pdf

http://www.ledet.com/margulis/Numbers.pdf

Deke McClelland has a video that uses Calculations to improve a mask he's creating in a video on Lynda.com. It's one of the free videos that don't require a Lynda.com membership to watch. Click on "A first peek at the Calculations command" under Advanced Blending.

http://movielibrary.lynda.com/html/modPage.asp?ID=506

There are a number of posts here on site that have used "Apply Image" - let me see if I can find some of them for you using our Search function.

Here's a thread that links to a tutorial on our site (see the link in the first post by the author MyPhotosoft) and also has some discussion with an explanation about "apply image" by member Graphics23.

Often it's hard to have specific questions about a new subject until we learn a bit about it -- after viewing/reading thru some of the materials, you may want to post some more questions here.

http://www.retouchpro.com/forums/rp-tutorials/18935-correcting-overexposed-detail-using-channels.html#post171015

Thanks to both Adam and CJ. I watched the McClelland video and I also went to the link of Graphics and followed his instructions and I can see some improvement in my image. I need to learn more about these functions. Adam makes reference to Katrin Eisman's book. She works through one scenero on page 218 using Apply image. My problem is that I don't understand the concept. I just need to practice at more which is true about a lot of the Photoshop capabilities.

Thanks again for your help
Dave Bliss

...My problem is that I don't understand the concept. I just need to practice at more which is true about a lot of the Photoshop capabilities.... Dave Bliss

Do I understand you correctly that you know HOW to use "Apply Image" and "Calculations", but still aren't sure WHEN and WHY to use them? If so, you're a member of a probably large club. If you have any questions about the procedure involved when you choose to apply them, let's clear that up first.

As to WHEN and WHY -- I know they can be helpful in creating masks when there are elements in more than one channel that would be helpful in creating a needed mask. I have read on Katrin Eismann's site that their use is less important now -- "Today with the use of layers and blending modes many of their results can be achieved with more ease but, these commands still offer useful methods for creating image composites and building masks that maintain fine tonal and edge detail."
Eismann lists their primary differences as:
• The Apply Image command uses the composite color image or single channel
as its source to create color images or channels. It cannot create a new
document, channel, or layer.
• The Calculate command lets you choose a source from any open image with
the same image resolution, but it only uses a single grayscale channel.
Calculate creates a new channel, black-and-white document, or an active
selection but never a color file.

There is a sample chapter from Katrin Eismann's book online, and it includes some info about Chris Tarantino (a pro member here) use of apply image when correcting color "Interchannel Color Correction (http://www.peachpit.com/articles/article.aspx?p=101197&seqNum=10&rl=1) ". Take a look.

The apply image function is pretty much (as I understand it) like using blend mode on layers. Since you can't have blend modes in the channels the Apply Image does the same thing.

For example open up a regular picture in Photoshop, then duplicate that layer, on the new layer change the blend mode to multiply and set the opacity to 50%. Notice how the density of the image has increased. Using Apply image is a lot like taking to copies of your red channel and setting the top to multiply. Using apply image the red channel now has more contrast and and more density.

You can take it a step further but instead of using two red channels you can take information from the red channel and mix a percentage of it into your blue channel. Further, you can use blend modes to manipulate the tones even more. The trick is to add the right amount of tonal information to build detail and still have the correct colors. (to much and you could have too blue or too yellow of an image)

Calculations also does this channel mixing, but only outputs a new separate channel or document, while the apply image effects the RGB channels (or CMYK etc..)

To understand this process of mixing channels you may want to brush up on what channels really are, after all when you snap a photo the camera never records any color, just grayscale values separated in channels, but combined they produce the color.

If you post your image I can take a look at it wed night and look at the individual channels.

*edit, I let me reply sit in the quick reply box for like 7 hours and forgot to post lol, maybe this will add to what CJ was saying