# Measuring the 16-bit difference

## Video: Measuring the 16-bit difference

All right, glad to see you back for more here because this is kind of a tough topic to wrap your mind around. So we have got an 8 bit per channel image open here on the left and a 16 bit per channel image open here on the right. The images in question are Pen&ink (8bit). jpg and Pen&ink(16bit).tif and they are both found inside of the 17_16bitHDR folder, just to keep things simple. To go ahead and throw them in the folder called 17_16bit_HDR that will simplify things. Anyway it's our folder naming convention so there you go but I have got these two images open there and functionally identical scans. Well, at least they are scans of the exact same artwork. And they are both scanned using the same model scanner the only difference is I saved one of the scans in the 8 bit per channel space and I saved the other scan in the 16 bit per channel. So we have up to 256 different brightness values over here on the left and we have as many as upwards of 32000 brightness values over here on the right.

## Measuring the 16-bit difference

All right, glad to see you back for more here because this is kind of a tough topic to wrap your mind around. So we have got an 8 bit per channel image open here on the left and a 16 bit per channel image open here on the right. The images in question are Pen&ink (8bit). jpg and Pen&ink(16bit).tif and they are both found inside of the 17_16bitHDR folder, just to keep things simple. To go ahead and throw them in the folder called 17_16bit_HDR that will simplify things. Anyway it's our folder naming convention so there you go but I have got these two images open there and functionally identical scans. Well, at least they are scans of the exact same artwork. And they are both scanned using the same model scanner the only difference is I saved one of the scans in the 8 bit per channel space and I saved the other scan in the 16 bit per channel. So we have up to 256 different brightness values over here on the left and we have as many as upwards of 32000 brightness values over here on the right.

We probably don't actually have that many brightness values but we could have that many, put it that way. But it's safe to say, we don't have any more than 256 over here on the left and we have probably a couple of thousand really over here on the right and that's going to make a big difference when we go to edit the image and the edit that we need to apply, we need to increase the contrast of these images so that the dark lines are black, absolutely black and the white areas are absolutely white instead of gray as they are right now, these light gray areas.

So, let's go ahead and use the Levels command, I am going to first make sure that the image on left is active then I am going to press Ctrl+L or Command+L on the Mac to bring up the Levels dialog box and you can see this histogram right there and notice that there is essentially three different lumps in the histogram. This lump over here, this guy right there, that represents the dark lines inside of my artwork so that's the actual Pen&ink work and then this big hump over here on the right represents page white, this area right there and then this hump that represents all of those gray diagonal lines that are holding the photos into place on the photo album page.

So here is what we are going to do, I am going to increase the black point value beyond that first hump, well beyond it, in fact, I am going to take that black point value up to a 115 so anything with the luminance level of a 155 or darker becomes black and then I am going to drag the white slider not just beyond page white. Notice that leaves the photo album down here at the bottom of the screen. Let's go ahead and take it beyond the next hump as well which makes the photo album lines disappear. Good, and I am going to take the White Point Value down to a 150 so anything with a luminance level of a 150 or lighter becomes white. So all we have left is this little range of luminance levels right there that's going to get stretched across the entire histogram.

All right, I will go ahead and click OK to apply that modification. Now let's go over to Pen&ink(16bit).tif and I want you to press Ctrl+Alt+L or Command+Option+L on the Mac in order to replay that exact same levels modification. So notice it's taking to me using the exact same values as before as if zero is black, which is true in 16 bit as well but 255 for white that is strictly an 8 bit per channel convention it doesn't apply to 16 bit, it would be 32000 something for white and Levels goes ahead and talks to me in 8 bit per channel language no matter what bit depth I am working with. And that's true for a lot of commands inside of Photoshop.

They talk to you in 8 bit language even if you are working on a 16 bit per channel image but rest assured you are working on a 16 bit per channel image as you will see very shortly. So anyway exact same modification being applied and the two images as a result, I will go ahead and click on the OK button in order to accept that modification, look the same. They look the same before the modification, they look the same after the modification. The reason being of course, that we are viewing the images on a 8 bit per channel display device and so the device really can't show us the difference between these two images but we can see the difference between the two images using a histogram.

So check this out, I will go back to the original image and we might as well use the histogram in the Levels dialog box so I will press Ctrl+L once again and check that out. Notice these little whiskers down here at the bottom of the screen. Those represent all the gray values that are available to us and then this big line over here represents black and this big line over here represents white. Now the problem is that Photoshop goes ahead and scales everything in between so they just appear as tiny little whiskers even though there is tons of gray pixels inside of this image.

So what we are better off doing is selecting only the gray pixels and measuring them. And here is how we are going to do that, go ahead and cancel out of this dialog box. I want you to go over to the Magic Wand tool, grab the Magic Wand tool her from the toolbox and make sure these settings are enforced; The Tolerance value should be zero, Anti- Alias should be turned off, Contiguous off, Sample All Layers off, so all the check boxes off this time around Tolerance zero. And now click in the white pixel and that will select all of the white pixels inside of the image. Now I want you to press the Shift key and I want you to click on a black pixel like, let's click inside of the guys eye, sort of towards the middle of the eye. So Shift+Click on a Black pixel and that selects all of the Black pixels as well. So now all of the black pixels are selected and all of the white pixels are selected. None of the Gray pixels are selected.

Now I want you to go up to the select menu an chose Inverse. Now you don't have any White pixels or Black pixels selected, you only have gray pixels selected. And you can see the marching ants, go ahead and press Ctrl+H or Command+H on the Mac so that the marching ants stop animating on screen there. Then press Ctrl+L or Command+L on a Mac and those are your remaining gray values. Notice that they look like columns or at least longer hairs separated by big areas of space and those big areas of space represent gaps in the histogram areas where there are no continuous colors so we do not have continuous colors anymore. We have posterization, pretty bad posterization in fact as well. Go ahead and click Cancel in order to cancel out that dialog box, let's run through those same steps here in the 16 bit per channel image.

So I have gone ahead and selected all the white pixels, I am going to Shift+Click on the black pixels to select all of the black pixels as well. And then I am going to go up to the Select menu and choose the Inverse command and now only the gray pixels are selected inside the image, neither black nor white just the gray pixels in between. I am going to press Ctrl+H or Command+H on the Mac to stop animating the marching ants and then I am going to press Ctrl+L and get a load to this. Ctrl or Command+L, a nice full rich histogram. So we still have more than 256 luminance levels available inside of this image, despite our drastic modification.

As a result this image on right, even though it doesn't look any better on screen, is going to hold up better to further editing because at some point we would start noticing the difference and it's going to print better as well and it's going to up sample better and down sample better and everything else. Anything else you care to do it inside of Photoshop is going to go better, thanks to the fact that we are working with a 16 bit per channel image. So the practical up shot in this case is when you are scanning black and white line art always scan to 16 bit per channel, then any modifications that you make inside of Photoshop are essentially, really, non-destructive modifications, you are going to have a hard time, harming this image where you are going to have a very easy time harming the one over here on the left.

All right, so that's just an introduction to 16 bit. We are going to see more 16 bit color this time applied to a continuous tone full color photograph in the next exercise.

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#### This video is part of

190 video lessons · 26326 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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