rutt
Nov-16-2009, 06:58 AM
I've been doing a lot of B&W conversions recently and I get a lot of compliments on them. I have developed a workflow that I always use. I think it's really very simple. The results are particularly good for pictures of people against various backgrounds. Once mastered, it takes about 5 minutes per image or less, depending on how fussy you are. Unlike plugins and separate programs, you do have to understand some photoshop commands and color theory, but at least for me, that's part of the fun. As usual, all the basic ideas are due to Dan Margulis.
The workflow has three steps:
Convert to B&W by channel blending.
Curve to enhance contrast
Sharpen two ways for local contrast and sharpness
I'll go through these steps in detail with an example image taken by Alex Feldstein from this thread. (http://dgrin.com/showthread.php?t=150451):
http://www.ruttpix.com/photos/714944389_3kWjL-O.jpg
Unfortunately, it's not full sized, so our results won't be quite what they would be if it were. I'll make an effort to demonstrate on more images in the future, undoubtedly some full sized.
1. Convert to B&W by channel blending
Let's look at the RGB channels:
http://www.ruttpix.com/photos/714937361_VgSjC-O.jpg
Red
http://www.ruttpix.com/photos/714937296_bCiGu-O.jpg
Green
http://www.ruttpix.com/photos/714937267_3dYfB-O.jpg
Blue
Which of these is the best portrait? As usual, there really is no contest. Facial details live in the green channel. Red is nearly completely blown in the face and blue is too harsh and noisy. So we might be tempted just to use the green channel and be done with it, which is often the right idea with portraits. But in this case, the red channel has soething going for it: better contrast in the sky, so we'd like to get the best of both worlds: the face from the green and sky from the blue.
Theoretical digression, skip if you like. Why does the red channel have more contrast in the sky? Skys are blue and white, so you might think you'd find them in the blue channel. But the sky is almost completely uniform in the blue.
The reason is that in order for something to be either blue or white, the blue channel has to be bright. White is blue+grreen+red. If something is just blue, there will be no red. If it is white, it needs red as well as blue. So the contrast comes from the red channel.
Similarly, faces are basically red. That means that the contrast won't be found in the red channel. More green make lighter parts of faces. Less green will make the shadows.
End of digression.
It's easy to get the best of both worlds by layering the red channel over the green channel in Darken blending mode. Like this:
http://www.ruttpix.com/photos/714943641_Gt2JJ-O.jpg
And the resulting image:
http://www.ruttpix.com/photos/714976375_mvAg3-O.jpg
Here I copied the red and green channels each into their own layer and set the blending mode of the topmost layer to Darken. This blending mode uses the layer only where it is actually darker than the layer below. Since the man's face is red, it's pretty much guaranteed to be lighter in the red, and hence not used. But the sky is darkest in the red, especially the blue parts, so we get the nice contrasty sky. And it was painless, not brush work or selections. We relied only on the basic properties of the image.
Theoretical digression, skip if you like. This particular kind of blending, darken or lighten, is unique to digital manipulation. You can't do this particular thing in the darkroom, at least not easily. Filters can highlight one channel or another, but can't do this kind of logical comparison. So this is not a film look. In the darkroom, it would probably require multiple exposures with dodging and burning. Hooray for digital!
End of digression.
So far, so good. I have an action which aides to to getting to this point. Pick it up here (http://colortheory.us/BW/B&W.atn). We're now down with channel blending. Flatten the layers and let's move on.
2. Curve to enhance contrast
Curves often seem daunting at first, but they are huge creative tool and learning to use them will give you far more control over your results than any single other PS technique you can learn.
One thing to notice here, I have my curves set to have darkness on the right, which is not the PS default. The reasons for this are not really relevant, just notice it.
So, I make a new curves adjustment layer for this image. In CS4, it shows the histogram in the background and I can instantly see that the image doesn't have a white point:
http://www.ruttpix.com/photos/714943623_3QdUy-O.jpg
In older versions of PS, you won't have this histogram directly on the curves adjustment layer, but it's not that important. With or without the histogram, we want to find out decide what will be the lightest and darkest points of the image so we can use the full range of contrast available. This will almost always make the image look better and sharper with true rich blacks and good detail where we want it. In this case, the lightest part of the image we care about is on the man's shirt. For older versions of PS, you can discover this by holding down the Apple or Alt key and mousing over the image. You'll see the spot on the curve. For CS4, with a curve adjustment layer, you have to enter a mode to do this. There is an icon of a finger on the left side of the curves panel. Click it and then the curve will show the brightness of the point under the cursor.
Anyway, I've decided that I want s point on his shirt to be the lightest point in the image. I still want detail in the shirt, but there is nothing I care about that is brighter than the shirt. And his glasses are already black and I do care about them. So, I moved the light end of the curve inward to make the shirt point white. That's shown in the curve above, and here is the result:
http://www.ruttpix.com/photos/714937370_haeqc-O.jpg
This is a definite improvement, a lot less muddy, but we can do better. The punchline of this image is the man's face and the sky, not the shirt nor the glasses. So we want to use more of our contrast budget to enhance the face and sky than on the shirt and glasses. By mousing around on the curve as above, it's evident that the face and sky live in the midtones. If we get the curve to be steep there and shallower at the two ends, we'll allocate our budget appropriately.
http://www.ruttpix.com/photos/714943651_pG4j5-O.jpg
http://www.ruttpix.com/photos/714937280_AD4sa-O.jpg
This is an example of the classic "S-shaped" curve. Often it suffices just to pull up or down one point on the curve, depending on where we want the contrast. Another thing to notice is that fairly small changes to the curve can have dramatic impact on the image. You have to learn to be pretty subtle.
At this point, we are done with curves, time flatten the layers and to move along to the next step.
3. Sharpen two ways for local contrast and sharpness
Before we get started with this, I need to issue a warning. I only have small low resolution image to work with. That greatly influences the choice of radius to use for sharpening, so beware. I'll give more some guidelines for full sized images, but the real trick for sharpening is to look at see how it works instead of fixating on some number to use.
OK, I like to sharpen my images twice, once with a very wide radius and very low amount (called "HIRALOAM, or High Radius Low Amount" sharpening) and a second time with a much smaller radius and larger amount (called "conventional sharpening".)
HIRALOAM sharpening emphasized the large features of your image and also adds local contrast. It works even for somewhat soft or noisy images. It's something you will be happy to learn.
Make a duplicate layer and open Filter->Sharpen->Unsharp Mask. Set the Amount to its maximum value, 500 and the Threshold to 0. Now increase the Radius until you see the large features of the image emphasized but not so much that they blend into one another.
http://www.ruttpix.com/photos/714937348_4WkLT-O.jpg
http://www.ruttpix.com/photos/714943624_nRpCh-O.jpg
(In full sized images, the radius might be somewhere between 10 and 50.) Of course this is pretty ugly, not what we want at all, but we can see that it emphasizes the large features at the expense of detail.
So this is a lot too much of a good thing. Turn down the Amount until the obvious halos disappear, usually around 35. It might still be a little harsh looking, but we're not quite done yet.
http://www.ruttpix.com/photos/714937297_NsiLC-O.jpg
Unsharp mask works by making light and dark halos. It surrounds dark things with light halos and dark things with light halos. You can find out a lot more about this here (http://dgrin.smugmug.com/gallery/1104535) and here (http://www.dgrin.com/showthread.php?t=10409). Suffice to say, the light halos are usually a lot more noticeable than the dark ones, so it's usually a good idea to tone them down more than the dark ones. Duplicate the sharpened layer and blend one layer in Darken mode and one in Lighten mode. Then you can reduce the opacity of the Lighten layer, say to 50%, effectively dimming the light halos while keeping the dark ones.
http://www.ruttpix.com/photos/714937310_S7XJD-O.jpg
At this point you may want to fine tune the amount of sharpening even further. It's just a matter of adjusting the opacity sliders.
In addition to emphasizing the large features of the image, it's often a good idea to do conventional sharpening to emphasize the fine details as well. In this particular image at this resolution, there's not much that's going to really change. Follow the links above for details. Here is my final version:
http://www.ruttpix.com/photos/714937339_MFP87-O.jpg
It's picked up some whisker detail, maybe too much. A lower amount or lighten/darken layers might look better to another eye.
The workflow has three steps:
Convert to B&W by channel blending.
Curve to enhance contrast
Sharpen two ways for local contrast and sharpness
I'll go through these steps in detail with an example image taken by Alex Feldstein from this thread. (http://dgrin.com/showthread.php?t=150451):
http://www.ruttpix.com/photos/714944389_3kWjL-O.jpg
Unfortunately, it's not full sized, so our results won't be quite what they would be if it were. I'll make an effort to demonstrate on more images in the future, undoubtedly some full sized.
1. Convert to B&W by channel blending
Let's look at the RGB channels:
http://www.ruttpix.com/photos/714937361_VgSjC-O.jpg
Red
http://www.ruttpix.com/photos/714937296_bCiGu-O.jpg
Green
http://www.ruttpix.com/photos/714937267_3dYfB-O.jpg
Blue
Which of these is the best portrait? As usual, there really is no contest. Facial details live in the green channel. Red is nearly completely blown in the face and blue is too harsh and noisy. So we might be tempted just to use the green channel and be done with it, which is often the right idea with portraits. But in this case, the red channel has soething going for it: better contrast in the sky, so we'd like to get the best of both worlds: the face from the green and sky from the blue.
Theoretical digression, skip if you like. Why does the red channel have more contrast in the sky? Skys are blue and white, so you might think you'd find them in the blue channel. But the sky is almost completely uniform in the blue.
The reason is that in order for something to be either blue or white, the blue channel has to be bright. White is blue+grreen+red. If something is just blue, there will be no red. If it is white, it needs red as well as blue. So the contrast comes from the red channel.
Similarly, faces are basically red. That means that the contrast won't be found in the red channel. More green make lighter parts of faces. Less green will make the shadows.
End of digression.
It's easy to get the best of both worlds by layering the red channel over the green channel in Darken blending mode. Like this:
http://www.ruttpix.com/photos/714943641_Gt2JJ-O.jpg
And the resulting image:
http://www.ruttpix.com/photos/714976375_mvAg3-O.jpg
Here I copied the red and green channels each into their own layer and set the blending mode of the topmost layer to Darken. This blending mode uses the layer only where it is actually darker than the layer below. Since the man's face is red, it's pretty much guaranteed to be lighter in the red, and hence not used. But the sky is darkest in the red, especially the blue parts, so we get the nice contrasty sky. And it was painless, not brush work or selections. We relied only on the basic properties of the image.
Theoretical digression, skip if you like. This particular kind of blending, darken or lighten, is unique to digital manipulation. You can't do this particular thing in the darkroom, at least not easily. Filters can highlight one channel or another, but can't do this kind of logical comparison. So this is not a film look. In the darkroom, it would probably require multiple exposures with dodging and burning. Hooray for digital!
End of digression.
So far, so good. I have an action which aides to to getting to this point. Pick it up here (http://colortheory.us/BW/B&W.atn). We're now down with channel blending. Flatten the layers and let's move on.
2. Curve to enhance contrast
Curves often seem daunting at first, but they are huge creative tool and learning to use them will give you far more control over your results than any single other PS technique you can learn.
One thing to notice here, I have my curves set to have darkness on the right, which is not the PS default. The reasons for this are not really relevant, just notice it.
So, I make a new curves adjustment layer for this image. In CS4, it shows the histogram in the background and I can instantly see that the image doesn't have a white point:
http://www.ruttpix.com/photos/714943623_3QdUy-O.jpg
In older versions of PS, you won't have this histogram directly on the curves adjustment layer, but it's not that important. With or without the histogram, we want to find out decide what will be the lightest and darkest points of the image so we can use the full range of contrast available. This will almost always make the image look better and sharper with true rich blacks and good detail where we want it. In this case, the lightest part of the image we care about is on the man's shirt. For older versions of PS, you can discover this by holding down the Apple or Alt key and mousing over the image. You'll see the spot on the curve. For CS4, with a curve adjustment layer, you have to enter a mode to do this. There is an icon of a finger on the left side of the curves panel. Click it and then the curve will show the brightness of the point under the cursor.
Anyway, I've decided that I want s point on his shirt to be the lightest point in the image. I still want detail in the shirt, but there is nothing I care about that is brighter than the shirt. And his glasses are already black and I do care about them. So, I moved the light end of the curve inward to make the shirt point white. That's shown in the curve above, and here is the result:
http://www.ruttpix.com/photos/714937370_haeqc-O.jpg
This is a definite improvement, a lot less muddy, but we can do better. The punchline of this image is the man's face and the sky, not the shirt nor the glasses. So we want to use more of our contrast budget to enhance the face and sky than on the shirt and glasses. By mousing around on the curve as above, it's evident that the face and sky live in the midtones. If we get the curve to be steep there and shallower at the two ends, we'll allocate our budget appropriately.
http://www.ruttpix.com/photos/714943651_pG4j5-O.jpg
http://www.ruttpix.com/photos/714937280_AD4sa-O.jpg
This is an example of the classic "S-shaped" curve. Often it suffices just to pull up or down one point on the curve, depending on where we want the contrast. Another thing to notice is that fairly small changes to the curve can have dramatic impact on the image. You have to learn to be pretty subtle.
At this point, we are done with curves, time flatten the layers and to move along to the next step.
3. Sharpen two ways for local contrast and sharpness
Before we get started with this, I need to issue a warning. I only have small low resolution image to work with. That greatly influences the choice of radius to use for sharpening, so beware. I'll give more some guidelines for full sized images, but the real trick for sharpening is to look at see how it works instead of fixating on some number to use.
OK, I like to sharpen my images twice, once with a very wide radius and very low amount (called "HIRALOAM, or High Radius Low Amount" sharpening) and a second time with a much smaller radius and larger amount (called "conventional sharpening".)
HIRALOAM sharpening emphasized the large features of your image and also adds local contrast. It works even for somewhat soft or noisy images. It's something you will be happy to learn.
Make a duplicate layer and open Filter->Sharpen->Unsharp Mask. Set the Amount to its maximum value, 500 and the Threshold to 0. Now increase the Radius until you see the large features of the image emphasized but not so much that they blend into one another.
http://www.ruttpix.com/photos/714937348_4WkLT-O.jpg
http://www.ruttpix.com/photos/714943624_nRpCh-O.jpg
(In full sized images, the radius might be somewhere between 10 and 50.) Of course this is pretty ugly, not what we want at all, but we can see that it emphasizes the large features at the expense of detail.
So this is a lot too much of a good thing. Turn down the Amount until the obvious halos disappear, usually around 35. It might still be a little harsh looking, but we're not quite done yet.
http://www.ruttpix.com/photos/714937297_NsiLC-O.jpg
Unsharp mask works by making light and dark halos. It surrounds dark things with light halos and dark things with light halos. You can find out a lot more about this here (http://dgrin.smugmug.com/gallery/1104535) and here (http://www.dgrin.com/showthread.php?t=10409). Suffice to say, the light halos are usually a lot more noticeable than the dark ones, so it's usually a good idea to tone them down more than the dark ones. Duplicate the sharpened layer and blend one layer in Darken mode and one in Lighten mode. Then you can reduce the opacity of the Lighten layer, say to 50%, effectively dimming the light halos while keeping the dark ones.
http://www.ruttpix.com/photos/714937310_S7XJD-O.jpg
At this point you may want to fine tune the amount of sharpening even further. It's just a matter of adjusting the opacity sliders.
In addition to emphasizing the large features of the image, it's often a good idea to do conventional sharpening to emphasize the fine details as well. In this particular image at this resolution, there's not much that's going to really change. Follow the links above for details. Here is my final version:
http://www.ruttpix.com/photos/714937339_MFP87-O.jpg
It's picked up some whisker detail, maybe too much. A lower amount or lighten/darken layers might look better to another eye.