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Another function of the Reduce Noise Filter is that it allows you to smooth away JPEG compression artifacts inside of an image. Now the image that we are looking at on screen right now is called ornamentaldetail.jpg. It's inside the 12 Blur Average Folder and this is an image that I shot myself. I wouldn't do this to anybody else's image and not only was it pretty darn compressed in the first place but then I turned around and saved the image with a JPEG quality setting of zero which is the lowest setting you can apply from Photoshop.
And that means even though the image is 1.5 Megs in memory it's not very big but still 1.5 Megs it only takes up 50K on disk. That's how much you compress down. But it looks like garbage because of this heaping helping of JPEG compression. Now I am going to go ahead and zoom in on this little detail here. Notice this little highlight that's in the lower right corner of this generic holiday ornament here and you can see it's supposed to be a smooth highlight but it's anything but smooth it's choppy, it's made up of a bunch of gargantuan squares.
Now these squares measure 8x8 pixels alright so 8 pixels wide, 8 pixels tall this is how Photoshop invokes its JPEG compression. And the idea is it locks down so JPEG compression is lossy meaning that it goes through and rewrites the pixels inside of an image. It locks down in these 64 pixel blocks, it locks down the top left pixel, locks down its color and then it tries to change the color of the other 63 pixels based on this upper left pixel.
So it tries to change them to be slightly similar is basically the idea and it makes for smaller code on disk and it also makes for a choppier image on screen and in print. Now what's amazing about it even though we have this enormous amount of JPEG compression applied to this image to the extent that we have just a bunch of big squares here when we are zoomed in this tight, we are zoomed into 1200%. If I were to zoom out or press Ctrl Alt 0 or Command Option 0 to zoom out to the 100% view size notice how amazingly smooth that actually is.
Now it's not entirely smooth you can see that there is a lot of compression artifacts there but it doesn't look like a bunch of squares quite to the extent that it did when we were zoomed in. And the amazing thing about JPEG and the way that it works is it does a heck of a job of fooling our eyes from a distance so as long as you stick with a high resolution file you can get away with a lot of compression not this much of course but you know pretty much. Alright anyway let's say that your image is either highly compressed like this one or it's not all that compressed, it just has some light compression artifacts inside of it but you want to be able to sharpen the image or otherwise modify it without enhancing those compression artifacts.
What do you do? Well I am going to once again Shift+Tab away my palettes and press the F key a couple of times in order to switch this Full Screen mode here and I am going to scroll the image over to the right a little bit. Now the Reduce Noise Filter appears at the top of my Filter menu because it was the last filter I applied so I can just go ahead and press Ctrl Alt F or Command Option F on the Mac in order to bring up the reduce noise dialog box and once again I am going to move it off to the side so we can maximum use of this small format screen.
And I am going to really lay on the reduce noise function here. First of all I am going to turn on Remove JPEG Artifact because that does a better job, it's a subtle function as it turns out but that will go through and do a better job of focussing the command's energies on the contrast areas between one 64 pixel block and the next 64 pixel block. Now I am going to really maximize my settings by of course turning the strength up to 10, taking the Preserve Details Value down to 0.
I am going to take the Reduce Color Noise function up to 60% and I am going to raise Sharpen Details just a little bit here because we just want a little bit of sharpening applied to the image because we are losing so much information. Now in addition to remove JPEG artifact here we have another control. At the top of the dialog box you can see Advanced and watch this area when I turn on the Advanced Radio button. We now get two tabs overall and we have already seen these controls and then per channel which allows us to modify the image on the channel by channel basis. Now I am going to click over here so that we can see this weird little highlight and also we can see the red channel of the image and you can see the compression artifacts are by far worse inside the red channel.
Now you can apply various settings to the red, green and blue channels independently if you want to, I am just going to focus on red channel here by raising the strength to 10 and reducing Preserve Details to 0 so that we are smoothing over as much as we can inside this image and you can see how much smoother the red channel is as a result. Now I am going back to overall and because we have done so much work on red channel I figure we can afford to take the strength value down a little bit, I am going to take it down to 5 actually and I am going to take the Preserve Details value up to 50% in order to raise that so that we get some of our details back inside the image.
And notice even though we are getting the details back in this region right here you can see that we are still getting rid of a lot of the compression artifacts, we are smoothing away a lot not all of course because they were so bad in the first place but we are doing a pretty darn good job of smoothing them away all things considered. Okay let's go ahead and save our settings and I will click on that little floppy disk icon and I will enter Really Bad Artifacts or something along those lines here and then I will click OK. In order to accept those new settings, I will choose the new settings of course to make sure that I don't overwrite routine noise when I click the OK button and now I click OK and this is the result of having applied that filter, this is before and this is after.
An amazing actually an amazing transformation of this heavily compressed image thanks to that awesome powerful reduce noise filter.
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