# Mastering Calculations

## Video: Mastering Calculations

Our final method for selecting a complex foreground image set against a busy background is to take multiple stabs at the image, poor image using the Calculations command. So for example, we might first try to select the green regions inside of the macaw here using one calculation and then we will select the red area this red tuft using another calculation, and then we will merge those two calculations using a third calculation, and then we will approach the beak using a fourth calculation and then we will try to merge that with the other two using a fifth calculation and so on and so on.

## Mastering Calculations

Our final method for selecting a complex foreground image set against a busy background is to take multiple stabs at the image, poor image using the Calculations command. So for example, we might first try to select the green regions inside of the macaw here using one calculation and then we will select the red area this red tuft using another calculation, and then we will merge those two calculations using a third calculation, and then we will approach the beak using a fourth calculation and then we will try to merge that with the other two using a fifth calculation and so on and so on.

So basically you might end up applying a dozen calculations to a single image in order to select it. Now it does take a some more reasoning skills. You have to gain some comfort with the Calculations command, but as you will see it is the most automated approach, and it also tends to deliver better results than High Pass, because you are asking Photoshop to do the work for you instead of making the decision on your own. So instead of going brain dead like with and High Pass and laborious like with High Pass you are going intelligent using Calculations and you are saving yourself some time and effort and maybe making a better mask as a result. But you've got to be able to reason your way through it. Now it's not rocket science. And I am just going to ask you to use three different blend modes here over the course of next couple of exercises.

So here I am, I am working inside of Military macaw.jpg. It's found inside of the 16 Tough Stuff folder. We are back to the original military macaw. It doesn't alpha channels or any paths. And the reason is that we are going to be filling this image up with new channels. As I said, let's start with the green, that's the best place to start because he has got so much green. After all he or she I don't really know the gender of this animal. So let's check out the channels, control one red, fine. It's kind of the blend channel, although it's bright where the tuft is concerned and obviously it's bright where the white area is concerned, but not a lot of contrast elsewhere.

And here is green, lots of contrast between the green of the animal and the background and lots of contrast overall. Then of course blue which is very dark inside of the beast, and I am not sure if you can call a bird a beast. But still, never call him a fish, that's where I draw the line. Now I think we have got the most contrast between green and blue. So the most difference between those channels where the green portion of the animal is concerned so that should make you think difference mask, right? Because the difference mask is going to find the areas of greatest difference.

So let's take advantage of that. I will go ahead and press Ctrl+~ or Command+~ in order to return to the RGB composite image. Let's go up to the Image menu, choose the Calculations command. And I am going to go ahead and change the first channel to green. Your image should of course be Military macaw in both, Source 1 or Source 2 layers background, because that's all we get to work here. Channel one should be green, channel two should be blue and Blend mode should be difference way down here, La Difference. We will get this effect right here which looks great. It's the green of the bird against the black background. We have turned the green of the bird white and everything else, everything that's not green is basically turned black on this, which is awesome. So go ahead and click OK in order to accept that new alpha channel and you can confirm that you have got a new alpha channel by going down here to the bottom Channels palette.

Let's call this green stuff or something along those lines, because it's the green stuff in the bird. Let's press Ctrl+L for the Levels command, Command+L on the Mac because after all we need to increase the contrast and I am going to make the black point something 20, it looks pretty good and let's make the white point something like 90 actually. Let's take it down pretty light. I think this looks very nice. And we've made the area inside the green portion of the bird very bright indeed. We have really highlighted it. It was very easy to select using Calculations. Let's click OK.

Next door to the green portion of the bird is the red tuft right there. So moving counter-clockwise around the bird once again. There is the red tuft. Let's go ahead and try to select it. We are still going to stick with a difference mask I think, because in a Red channel we have got a light tuft and in both the Green channel and the Blue channel, we have a dark tuft. So we should be able to use Red along with either Green or Blue in order to get a nice difference mask, in order to isolate that redness. So let's go back to the RGB image, go up to the Image menu, choose Calculations, it probably will go ahead and show you your last applied settings. Go ahead and change the Source 1 channel to Red and then we've got the Source 2 channel set to Blue. Let's try just for the heck of it. Let's try Green and see how, that looks that's nice.

We only have the tuft selected this time. That's great. Blending should be difference of course. Opacity 100%. All the check boxes are off except Preview. Go ahead and click OK in order to accept that new channel. Let's go ahead and name it red stuff of course and let's go ahead and increase the levels as well by pressing Ctrl+L for the Levels command. That's Command+L on a Mac. I might as well try 90 again. Let's see how that works. That works pretty darn good. We've got a very bright tuft. And I am going to take the black up to like 25 this time around. The exact values aren't all that important and I would just say mess around with until you get a very bright tuft like this. But if you want to follow along with me, this is what I have done 25 and 90.

Click OK and now we need to combine green stuff with red stuff in order to select as much of the bird as possible. So I am going to select Green Stuff alpha channel there. I am going to go up to the Image menu. I am going to choose Calculations yet again, and this time when we are combing two masks we each other, you know the mode. First of all we want to set one channel to Green Stuff, the other channel to Red Stuff. The mode we want to apply ain't Difference, although it doesn't half bad, but what we really want is green. Green is the mask combiner, and look what we get.

Nice, nice bird. Click OK in order to accept that. Grab your Dodge tool friends, make sure that Range is set to Highlights and let's merge these two guys together. So, the seam that is being created here, we want to get rid of the seam. I might as well just go ahead and use Lasso tool. Let's check here. What is this? Is this in or out of the tuft? Let's press Ctrl+~, Command+~ on the Mac. That's inside the bird. All right, let's go back. I think we are working on the sixth channel now. So Ctrl+6 or Command+6 on a Mac and I am going to Alt click round this region to select it. I just want to make sure that we are doing a good job here.

And grab all this garbage. And this area too, go ahead and select this and it's I and stuff like that and fill that with white by pressing Alt+Backspace or Option+Delete. Now we are doing pretty good. We have some massive horrible posterization down here that we can deal with later. We have got a very nicely selected head region. I am going to add to that selection a little bit and press Alt+Backspace again. But the bill, what do we do about the bill? I mean check it out. Here is Red channel, here is the Green channel, here is the Blue channel. It could be the exact same bill, it's just getting darker and darker, but certainly we don't have difference to work with. We can't say wow! We've got light bill in one channel and a dark bill on the other channel. So we are going to have to work with a different calculation this time. I will show you that calculation in the next exercise.

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#### This video is part of

190 video lessons · 26324 viewers

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2h 13m
1. The Odyssey Continues
2m 39s
2. Mapping one image onto another
7m 12s
3. Making a custom contrast mode
7m 10s
4. Luminance blending
8m 40s
5. Forcing the visibility of underlying layers
4m 4s
6. Adjusting the appearance of clipped layers
4m 34s
7. Selecting a Blend If channel
6m 12s
8. Enhancing highlights by hiding them
5m 9s
9. Smart Object first, layer mask second
7m 22s
10. The Fill Opacity Eight
4m 30s
11. Blending Smart Filters
7m 24s
12. Cleaning up edges
7m 39s
13. More fun with luminance blending
6m 22s
14. A first peek at the Calculations command
12m 11s
15. Masking a softly focused model
11m 46s
16. Moving layers and masks between images
7m 35s
17. Matching colors
9m 13s
18. Building transitional blended layers
6m 33s
19. Restoring normal colors
6m 50s

2h 33m
1m 20s
2. Rotating and stretching
7m 54s
3. A jet of motion blur
9m 18s
4. Keyboard tricks
5m 4s
5. Merging sky and landscape
6m 3s
6m 37s
7. Creating two windows into an image
7m 42s
8. Whitening teeth and adding other highlights
3m 46s
9. Mapping a texture onto an image
4m 1s
10. Isolating a texture with a layer mask
6m 44s
11. Welcome to the glass composition
3m 18s
5m 51s
7m 24s
9m 23s
15. Adding and blending the goldfish
8m 45s
16. Assembling the perfect group photo
5m 12s
17. Aligning photographs automatically
5m 26s
18. Masking in each person's best shot
5m 18s
6m 17s
20. Crafting the perfect final poster
5m 16s
21. From the improbable to the impossible
1m 56s
22. The fantastical "world of clones" effect
10m 0s
23. Upsampling and blurring a background
8m 39s
8m 3s
25. Choking edges with Gaussian Blur and Levels
3m 46s

2h 27m
1. The corrective power of masking
1m 6s
7m 22s
3. Brightening and neutralizing the eyes
8m 22s
5m 52s
6m 4s
6. Averaging away irregular flesh tones
3m 52s
7. Modifying specific colors
7m 46s
6m 0s
6m 40s
10. Adjusting the edges around fabric
7m 56s
11. Perfecting hair
9m 35s
12. Sharpening with a High Pass layer
10m 12s
4m 48s
8m 48s
15. Fashioning a depth map
6m 12s
16. Invoking a depth mask from Lens Blur
6m 38s
17. The perfect depth-of-field effect
6m 25s
18. Sharpening an archival photograph
7m 7s
8m 29s
20. Making a High Pass sandwich
7m 46s
6m 2s
4m 6s
4. ### 13. Channel Mixing and Other Tricks

2h 3m
1. Channel Mixer, I am your father!
1m 39s
2. Three ways to gray
7m 49s
3. Meet the Channel Mixer
8m 26s
4. Mixing a custom black-and-white image
7m 10s
5. Creating a professional-level sepia tone
5m 36s
6. Employing the Black & White command
8m 1s
7. Extreme channel mixing
4m 50s
8. The infrared photography effect
6m 43s
9. Taking shadows to the brink of black
3m 56s
10. Elevating highlights, leeching saturation
5m 58s
11. Deepening a black-and-white sky
5m 49s
12. Infusing luminance levels with color
5m 44s
13. Creating an opposing colorization scheme
4m 58s
14. Bolstering contrast with the Green channel
5m 37s
15. A tiny improvement to a terrific technique
7m 39s
16. The simple (but wrong) approach to red-eye correction
6m 39s
17. Channel-mixing red pupils
9m 18s
18. The expert approach to red-eye correction
5m 20s
19. Fixing problem coronas (pupil edges)
8m 9s
20. Making pupils match
4m 8s
5. ### 14. Calculations (aka Channel Operations)

2h 33m
1m 37s
2. The Calculations command
8m 16s
3. Blue Screen blending
7m 40s
4. Refining the Blue Screen mask
5m 53s
5. Brushing away color fringing
7m 24s
6. Locking the transparency of a layer
6m 22s
7. Nondestructive layer painting
7m 36s
8. How the Add blend mode works
8m 40s
9. How the Subtract blend mode works
6m 43s
10. Focus, noise, and other masking challenges
5m 33s
11. The Add mode in action
7m 51s
12. The Subtract mode in action
8m 25s
13. Comparing two channels with Difference
5m 24s
14. Enhancing the contrast with Curves
9m 11s
15. Gathering details with Apply Image
9m 43s
6m 6s
17. Dodge and Burn in action
8m 24s
18. Painting in the scalp
10m 1s
19. Painting away the face and chin
4m 53s
20. Compositing complementary images
4m 13s
21. Multiply, Minimum, Blur, and Apply Image
6m 40s
22. Crafting the final composition
7m 7s
6. ### 15. The Pen Tool and the Paths Palette

1h 57m
1. Mark of the Pen tool
1m 35s
2. The big paths project overview
6m 51s
3. How to make a path
8m 25s
4. Corner points and freeform polygons
8m 6s
5. Editing paths with the arrow tools
5m 2s
5m 15s
7. Adding and deleting interior points
6m 6s
8. Converting a path to a selection
3m 35s
9. Converting a path to a mask
6m 38s
10. Smooth points and control handles
8m 57s
11. Making cusp points
6m 0s
12. Combining paths in a vector mask
7m 55s
13. Turning a path into a shape layer
8m 57s
14. Combining paths to make a layer mask
7m 52s
15. Mixing layer and vector masks
10m 14s
16. Editing character outlines as paths
8m 39s
17. Using the Convert Point tool
7m 8s
7. ### 16. Masking the Tough Stuff

3h 17m
1. Where there's a will, there's a way
1m 18s
4m 10s
3. Applying the cast show
4m 2s
3m 7s
5. Applying an arbitrary map
3m 50s
7m 17s
7. Roughing in an object mask
6m 49s
8. Drawing missing details with the Lasso tool
4m 7s
9. Combining flesh and object masks
3m 53s
4m 10s
11. Selectively choking edges
3m 58s
12. Power duplication in Photoshop
7m 9s
5m 48s
14. Using Levels to mask iterations
3m 14s
15. Drawing an iteration boundary
4m 55s
16. Merging the best of two Levels iterations
4m 4s
17. More fun with Dodge and Burn
6m 14s
18. Fixing edges with the Pen and Stamp tools
7m 29s
19. Pulling from another file with Apply Image
4m 52s
20. Blending clipped layers independently
5m 43s
9m 22s
22. Amplifying the flame
3m 53s
23. Masking an image against a busy background
5m 15s
24. The Freeform and Magnetic Pen tools
6m 52s
9m 32s
26. A more deliberate approach to arb maps
10m 51s
27. Combining arb maps with paths
9m 28s
28. Masking with the help of the History brush
11m 38s
29. Creating a High Pass mask
7m 25s
30. Coloring in the outlines
8m 31s
31. Mastering Calculations
7m 29s
32. Subtracting and merging the beak
11m 6s
8. ### 17. 16-Bit/Channel and HDR

1h 33m
1. The meaning of bit depth (and why you care)
2m 50s
2. Scanning line art in 8-bit and 16-bit
5m 9s
3. Measuring the 16-bit difference
8m 9s
4. Correcting 8-bit images in the 16-bit space
9m 31s
5. Opening a raw image directly in 16-bit
6m 13s
6. Editing in Camera Raw, opening in 16-bit
8m 22s
7. 16-Bit/channel vs. 32-bit/channel (HDR)
8m 18s
8. Working with auto-bracketed photographs
5m 6s
9. Using the Merge to HDR command
6m 0s
6m 0s
11. Building a 32-bit sky mask
6m 29s
12. Properly exposing land and sky
4m 25s
13. Modifying a layer mask in 32-bit
4m 56s
14. Converting to and correcting in 16-bit Lab
12m 7s
9. ### 18. DMaps and Lighting Effects

2h 8m
1. Photoshop flirts with the third dimension
1m 13s
2. The displacement map
8m 24s
3. Making custom waves
7m 14s
4. Creating a Gaussian distribution
4m 32s
5. Using a two-channel displacement map
6m 28s
6. Creating a rustic edge effect
8m 21s
7. Distorting and shading with a DMap
6m 34s
8. Moonlight reflecting off water
8m 48s
9. Mapping the reflection onto the water
7m 7s
10. Dipping the moon into the water
6m 18s
11. Turning flesh into stone
7m 55s
12. Wrapping the stone around the face
7m 27s
13. Softening a displacement map
8m 5s
14. Making a repeating watermark pattern
9m 22s
15. 3D embossing with Lighting Effects
10m 48s
16. The amazing credit card type effect
6m 56s
17. Lightening the credit card letters
6m 16s
18. Wrapping the background around the text
6m 27s

1m 43s
1. Goodbye
1m 43s

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