Tone compression settings - HDR Efex Pro Tutorial

High dynamic range imaging is in large part all about tone compression. We're taking a dynamic range that is very great, very dark shadows, very bright highlights, a tremendous amount of contrast in the scene. And we're compressing that into a range of values that our cameras for example, could actually capture ,or that we're able to actually display through computer monitors or the printed image. HDR processing software, such as HDR Effects Pro, is largely about taking all of that information and compressing it down to a more typical range. A range that we would typically see in a photographic image. And we can control that tone compression. We can control how the image is processed and how the final result will appear. Those settings are found in the Tone Compression section on the right panel within HDR Effects Pro. At the moment I have all of my sections collapsed, but I can expand the Tone Compression section simply by clicking on it. Here we start off with two basic settings. We can adjust the overall tone compression. In other words, to what extent are we compressing the range of tonal values? If we don't compress much at all, then we're going to have some lost detail. The highlight detail will be lost because those bright highlights remain very bright, and the shadow detail will be lost because those shadows also remain very dark. But we can compress those tonal values, so they fit within the range of what we're able to have in a photographic image, by increasing the tone compression value. A negative value means that you're losing detail essentially in the image. And a positive value means that you're retaining or capturing detail based on the original captures that you created. So in this case, for example, you'll notice that I start to get a lot more information around the sun, but not any more information inside the sun itself. That area was blown out even in the darkest image I captured for this sequence. So I'm not able to invent information, I'm just taking the information from the individual captures that I'm assembling into an HDR image and determining to what extent if at all, I'm going to compress those tones in the HDR result. We can also adjust the strength of that effect. So I can increase the method strength in order to increase contrast in the overall photo and I can reduce the value in order to reduce contrast. The effect is something like sharpening. So if I take the method strength all the way down, you'll notice that we're effectively softening the image up a little bit, getting something of an ethereal glow to the image. If I increase the method strength, then you'll see that the detail is enhanced just a little bit. We're getting a little bit more contrast in the broad areas of the photo. We can also adjust the HDR method. The settings here can be collapsed or expanded, so by default you won't see these individual adjustments. But you can click the HDR method label in order to expand the settings here. First we have depth, and this allows us to really adjust the overall localized contrast enhancement for the photo. The far left button will turn the setting off, and as we increase the value, we'll get subtle depth, and then normal depth, followed by strong depth. And you can see that we get a little bit of an enhancement of localized contrast in the image as we increase that value. We can also determine the extent to which we want to enhance detail in the photo. We can soften the detail, creating an even stronger ethereal type of a glow, but we can also use a realistic setting, an accentuated setting, a detailed setting. Or the maximum value grungy, which as you can see, really adds quite a bit of texture to the photo, and in this case also serves to enhance the dust spots on the image sensor, when this image was captured. Finally, we have a drama setting and as the name implies, this allows us to increase or decrease the dramatic effect within the photo. The minimum value is flat, but we can increase these values through natural, deep, dingy, sharp and finally, grainy. So depending on whether you want a really dramatic interpretation of the photo or something a little bit more pedestrian, you have that control with the tone compression. By determining the overall range of tonal values that we're going to end up with in the final HDR image, as well as the subtleties of the actual processing of the tonal range and all of that tonal information in your HDR photo.