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Most of the images we work with use 8- bits of information to describe every pixel and for most images 8-bits of information is perfectly adequate. In fact, if you use more, you're going to limit the range of options that you have in terms of your filters available to you and you will ultimately end up converting your image to an 8-bit image in order to print it, unless you have a printer capable of accepting 16-bit output. So why would we use a 16-bit image? Because Camera RAW, the Camera RAW plug -in and programs like Adobe Lightroom favor the use of 16-bit images. What's the deal? If we come and look at our Mode we have 8-bit, 16-bit and 32-bit.
I'm not going to discuss 32-bit, 32- bit is exclusively for working with High Dynamic Range, HDR images and that's way beyond the scope of this course. But I am going to discuss 16- bit, so let's compare the two. I have the same image as an 8-bit and a 16-bit. It doesn't look much different, right? Well if we look at the Document Sizes we can see that the 16-bit is literally twice the size of the 8-bit.
If we look at the 16-bit we can see that not all of the filters are available to us, but what we gain with the 16-bit is the ability to pull our histograms or our curves around if we need to do a lot of editing to the image. Maybe we need to lighten the shadows significantly or maybe we need to mess around with the midtones a lot, in which case we can get away with far more, because we have far more data to work with before our image shows visible signs of degradation.
Let's see what I mean. So what I'm going to do now is I'm going to apply some adjustments to the 8-bit version and I'm not really looking too carefully at what's going on, on the screen, I'm just going to make a very, very heavy-handed adjustment here. I'm going to get my Midpoint slider and bring it over to the right and then I'm going to imagine that I'm doing this not as an adjustment layer, but as an image adjustment, so it's being burned directly onto the image itself. I'm going to make another Levels adjustment and just basically reverse what I did, get my Midpoint slider and move that back to the left.
And now I've introduce more contrast, but what I really want to show you is that I've introduced degradation. If we look at the shadow areas there we can see we now have banding in a way that we didn't have before. Now let's see what happens if I take these exact two Levels adjustment layers and copy them over to the 16-bit version, which I have open right here. I'm going to split my screen vertically and then I'm just going to drag these two on to the 16-bit version, and I know the image looks terrible.
That's not the point I'm trying to make here, I just want to show you what's going to happen when you do a little of editing. How will you might be able to get away with more if you are working with 16-bit? So I'm going to come to the 8-bit version and then choose Match Zoom and Location. So we got a direct comparison there. On the left we have the 8-bit version, look at that posterization and banding that's occurring in that shadow area, and in the 16-bit version the exact same adjustment being made, but with far less degradation.
So that's what a 16-bit file can do for you if you don't mind the extra weight of increased file size and the possible inconvenience of not being able to use the filters or all of the filters, then perhaps 16-bit is the way to go. And if you anticipate making a lot of edits to an image, do so with it as a 16-bit image, you can always convert it to an 8-bit image when you have done that heavy editing should you need to apply any filters to it.
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