Adobe Photoshop Image Restoration Tutorials
Basics / Unsharp Mask pt. 1
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Subtitles of the Movie (Adobe Photoshop Image Restoration / Basics / Unsharp Mask pt. 1)
Let us take a look now at some of the tools available to you to achieve sharpening and the way you do that. There is no adjustment layer for sharpening, so that is a direct pixel adjustment, which means you have to your original background layer and you go up to filter, and then go down to sharpen and you will see four choices there, the first one being just plain old everyday sharpen. It is a fixed adjustment, I do not know what the values are, but it really does not do much, you never use that one. That is just not going to do anything for you. Alright, then you go back, let us look at the second one, sharpen edges, so I do not use this one either, because it really has never given me the result that I have ever been looking for, but the theory behind that is that sharpening edges only affects the pixels that are say, along these areas or along these areas. The major contrasting areas, not inside the vagaries of the white here or the vagaries of the different tones of the red or here or even in the hair, it just affects the edges of the main areas of contrast in your overall image, like this area right here. That is sharpen edges and it really does not do that much, never really used it, never had that much success, you just get a better result by using other things. Sharpen more is exactly what it says, it sharpens more, it is a fixed value, you know and you just keep going sharpen more until you see what you like and I have never liked what I have seen, so I do not ever use it. The way you really use the sharpening function is the unsharp mask. Now the term unsharp mask is a little bit of a misnomer, there has been a lot of discussion about why they called it an unsharp, and no one really knows but that is what it is called. But this is what you use when you are going to do sharpening; this is the only place you go, do not do sharpening anyplace else, except maybe one other that I am going to show you, but this is where you are going to do ninety nine percent of your sharpening is the unsharp mask, because of the adjustments that you can make. Now again, we are going to use this image and we are going to refresh our memories just a bit, a hundred percent, two hundred, and let us say go out to three pixels and we see the result. You can see the result right here. But now, let us turn our attention not from what happens on the pixel level but let us look at what happens to the image itself, with the different intensities of sharpening that you can bring to bear and this is where life gets interesting because no one, that I have ever seen explains this to you, all they do is tell, well you sharpen with this or that value and this is what you are going to get. And you really need to have a grasp of what the original resolution of your photograph is. Now again, this is a seven megabyte image, it is a TIFF, three hundred dpi; this is a JPEG, seventy-two dpi, and it is a three hundred and seventy-one kilobyte image. There is a whole lot more color information here than there is here. Now I am going to put the exact same adjustments on both of these images and I want you to watch and see what happens to the result. Now this is two hundred percent, with a radius of three pixels and a threshold of three levels. Okay, three levels of brightness that is what it is going to do. Look at the distortion, look at the huge amount of distortion on the low-resolution image that results from those adjustment settings. This is before and this is after. This is not what you are looking for, this is an overly compressed image. Alright let us take the exact same settings and apply them to the high-res image and look, that is exactly what you are looking for. May be a little, just a tincture over, let us drop this back maybe down to 150, now that is perfect. Let us take it back to 200 just so that we can have our comparison. Take a low res image and a high res image, make your settings and apply those settings to both images and you will see exactly what I am trying to illustrate to you here. Let us go back to the low-res image and is that horrible? That is absolutely horrible. Now this photograph needs to be backed off to 100, a radius of point eight, and a threshold of zero, maybe, maybe 150. And again, you have to experiment with this; there is no mathematical certainty about sharpening, this is something that you do to taste, like so many other things in Photoshop, To me that looks about right. So the exact same setting has a world of a difference. Now you take this setting, a hundred and fifty percent at point eight radius, that is not eight pixels, that is point eight pixels, the threshold is zero. Let's see what happens to the high-res image with those settings; we cannot see it. The resolution is so high; the pixel density is so high on this image that you cannot see the result or the effect that sharpening, that the set of sharpening settings is having on the image. You just cannot see it, not on screen anyway, but you might be able to barely tell that if you printed these images out, but probably not. So sharpening the settings that you use is a function of the original resolution of your image. Please do not forget that and you will have a much better experience in your sharpening effects.
Tutorial Information
| Course: | Adobe Photoshop Image Restoration |
| Author: | Phil Hawkins |
| SKU: | 33473 |
| ISBN: | 1932072705 |
| Release Date: | 2004-01-27 |
| Duration: | 4.5 hrs / 77 lessons |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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