# [Wet Thumb Forum]-Photoshop processing algorithms



## 2la (Feb 3, 2003)

Okay, I need a little help from the Photoshop experts out there. I was processing my pics in the usual manner--cropping, reducing, auto-contrasting, and auto-color-correcting (when using flash)--when I happened upon an apparently powerful application called *Apply Image...(Multiply)*. I've read the help file and did a quick search on Google, but I can't really make heads or tails of it. I don't really know what it's doing to the image, but it seems to be doing it _really well_. So my question is two-fold:

1. What exactly does this processing algorithm do to the image? And

2. The results seem superior (at least in this instance) to those I get from my usual processing method. Given that it's hard to tell what the 'true, real-life' image looked like to start with, is there anything unethical in using this command (i.e., does it misrepresent the 'actual' image in any particularly exaggerated way?)?

Check out these images of one of my _Aspidoras pauciradiatus_ (cute little buggers)







that have undergone differential (or no) processing:









*Original, unprocessed*









*Auto Contrast* only









*Auto Color* only









*Auto Contrast* AND *Auto Color*









*Apply Image (Multiply)* only

Thanks for any input,

2la
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## 2la (Feb 3, 2003)

Well, it doesn't seem to work with every picture (though I still have the same questions as above). Take a look:









*Original, unprocessed*









*Auto Contrast* only, at 75%









*Apply Image (Multiply)* only

Any explanation for this?

_____


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## George Willms (Jul 28, 2004)

It looks to me like it's turning the brightness way down and the contrast up a bit.

George

5.5: mid-tech and maintenance, 29: high-tech, mid maintenance, 45 high: low-tech, low maintenance.

More complete tank specs in profile


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## Purpleamazon (Jul 23, 2003)

Hi 2la, I agree that it would appear as though it is turning the brightness was down and the contrast way up. There certainly isn't anything unethical about that, but is that really the desired effect that you want?

I'm not sure that you can't find more flexibility to control your image appearence throught the use of the levels adjusts commmand in photoshop, or better yet, through the use of curves. If you own the full version of photoshop, you can also get some pluggins that are made by Lumiquest that can make the image processing go a bit faster. You can also create actions yourself to repeat the same steps while correcting an image and just run the action each time that you want to make corrections. I rarely use the auto-adjust in Photoshop -- even the new CS version -- because it just isn't as good as levels or curves, although once in a while I will get lucky with it.

AKA: Aquanut at www.aquaden.com


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## mm12463 (Mar 5, 2004)

I have no problem with anyone using software to correct the images they have taken. Does anyone really think that the images we see daily are not corrected in the lab or on a computer? Even the ones you take to the local photo development place are altered.

The only issue I would have is if someone is entering a contest or intends to sell something or what not and has adjusted the photo to the point where it does not resemble the actual subject. That is misleading. Like making a double red Aggie way more colorful then it really is.

Mike
http://fish.silver-fox.us


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## 2la (Feb 3, 2003)

Thanks, all, for the input. As surmised it appears to work best on overexposed images, and I'll reserve its use in just such situations (which I do believe makes a positive difference). Purpleamazon, I'm not really familiar with the applications you mentioned and would greatly appreciate a very brief tutorial if you have the time, just to get me started--I can experiment the rest of the way.

Thanks again!

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## Purpleamazon (Jul 23, 2003)

2la, what version of Photoshop are you currently using? There are some major differences between versions so I'll need to know that before I can proceed with any advice.
Thanks,

AKA: Aquanut at www.aquaden.com


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## Justin Fournier (Jan 27, 2004)

2la, 

I was just looking over the pic of the Cory w/ Apply image (Multipy) only. Note how the barbels and the pectoral fins have stark contrast with the background. Compare that to the lampeye where the fins are transparent. They blend with the background. I would venture to guess when the comp automatically adjusts the pics, it does not setect the edges of the lampeye as well as the Cory. 

On the other hand, this could be totally wrong, as I am not photoshop expert by any means. Just thought I would share my observations.


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## 2la (Feb 3, 2003)

Justin, after going through several other pictures, I'm learning that my above observation was correct: Whatever the mechanism, it only works on overexposed pictures. Which is great--I've probably dumped dozens of raw photos already that I thought weren't salvageable. Wish I knew!

PA, I'm using version 7.0. Thanks for any help you can offer.

Regards,

2la

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## Purpleamazon (Jul 23, 2003)

2la, I can't really get into a step-by-step tutorial about using the adjustment layers here for accomplishing much of the same thing that you are trying to do, however I can point you to a good site with some tutorials at:

http://www.arraich.com/ps6_tips_basics1.htm

I would also recommend looking up adjustment layers in your photoshop manual. Essentially, what you are doing is creating a layer of information that sits on top of the original image and then making your adjustments there. It is a much more effective way of correcting an image than the auto fixes, including the one that you are currently using. In the adjustment layer, you'll be using a histogram that will tell you what your exposure is and it will give you the option of using a little slider to get the image closer to where you want it. Reading histograms is an important part of the digital photo world as most higher end cameras come with them built in their software and photoshop contains them in the program as well. They are not complicated at all to understand.

An even more precise method is the curves options but i find that they are harder to teach -- it just takes experimentation....

I run a large digital imaging project at a major museum in Washington, DC and we use only photoshop to restore and adjust out exposures post capture. I also work as a political event photographer and photojournalist and wouldn't dream of adjusting my images with anything other than photoshop. I think that the program is sometimes so deep that the average user finds it challening just to make simple adjustments. I took 3 semesters of it to get it mastered and now I use it everyday so it is pretty fresh in my mind. You'll be amazed at what you can ethically do to a digital picture to most accurately reflect what you initially saw through the viewfinder. It just takes some time and research.

Also, are you saving your files as PSD files and then making a JPEG copy for use on the web? Always capture at your highest resolution and then save that image as a TIFF or PSD image and work from there. You won't use valuable pixels during the compression process that way and will have better files to work with should you chose to print them again or you just want to preserve them. JPEGs are what we call "lossy" image file formats while TIFF and PSD and some others are "lossless."

Also, if you are familiar with darkrrom work and "dodging and burning" you can essentially accomplish the same thing in photoshop 7 by using those tools. Just don't do it on the original layer because it is best not to alter as many of the original pixels as possible -- make a duplicate of the background image and merge them later.

hope this helps....

AKA: Aquanut at www.aquaden.com


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## Purpleamazon (Jul 23, 2003)

2la, I hope that you don't mind, but I thought I would give you a little demo of what can be done in just a few minutes time in Photoshop. Here are your originals after having used the adjustment layer/levels commands, color correction and some dodging and burning.










and

AKA: Aquanut at www.aquaden.com


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## Purpleamazon (Jul 23, 2003)

And here is the next one -- notice that I burned out the water spots.... very quickly, I might add in photoshop.










I also corrected this to a cooler tone, but it could easily been corrected much warmer depending on your preference and the actual appearance of the fish.

AKA: Aquanut at www.aquaden.com


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## 2la (Feb 3, 2003)

Aquanut, thanks immensely for the advice, reference, and examples. I do hope you'll forgive me continuing to churn out amateur-level digital pics, though: I gave the Curves application a go at it, and it proved quite daunting! If I weren't neck-deep in the process of applying to residency programs, I'd have more time to experiment (though I'll give the Levels adjustment a quick try) in an effort to reproduce the quality of your post-capture productions (though I personally liked the presence of the "water spots," which were actually bubbles at the water's surface in the background). I almost think a formal class at a community college someday might be the most efficient route, but we'll see.

Thanks a TON again--I've bookmarked the hyperlink for future reference!

Regards,

2la

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## Purpleamazon (Jul 23, 2003)

LOL! I think your photos are good 2la! It is just the photoshop thing that has you (like it does most of us at one time or another!) And seriously, try the levels thing before you get too far into curves -- curves drove me nuts for the longest time!

And the water spots/lights/bubbles thing -- I liked them too, but I was quite sure what they were on my monitor and was hoping to demontrate how easy it is to remove actual water spots using the burn tool because so many of us wind up with them ruining otherwise good shots. And I agree - the class route is probably the quickest way to learn the program, however there is a "classroom in a book" book and CD that you can get tht has good tutorials as well.....

AKA: Aquanut at www.aquaden.com


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