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by Peter Ireland on Mon Jan 03, 2022 8:57 am
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I have noticed recently that I am seeing a lot of compression artefacts in my images, mainly along ridge lines, treetops and around birds. I also get some pixelation in my skies. The probable reason why I have just started noticing is the fact that I have just changed my monitor, or less likely, that I was just blind to these things:) I know it's a common problem, but, how come I can plainly see the artefacts in my and other people's work, yet others they're near enough artefact free. Am I doing something wrong? What do you do to limit or stop this from happening to your images?I know there is software that is supposed to help with this issue, but I don't want to go down that route.

I have attached a sample section of the artefacts which are on the tree line on the left-hand side.
Image
 

by SantaFeJoe on Mon Jan 03, 2022 11:18 am
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I’m curious about the answer. I can also see strong pixelation on the right hand side of the image, as well. (Actually, throughout the image). I see images posted here that show strong pixelation and artifacts, but others never seem to notice or comment on that. I think it’s more common than people realize. It will be interesting to see the comments and info here.

Joe
Learn the rules like a pro, so you can break them like an artist.  -Pablo Picasso
 

by Scott Fairbairn on Mon Jan 03, 2022 6:37 pm
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Too much compression and too heavy handed sharpening will causes artifacts. Minimal compression, or none is optimal. If you work on a jpg image, as in doing image adjustments and save it with compression, then work on it again, then it increases artifacts because every time you save a jpg and compress it, you lose quality. I’m not sure if you do that in your work flow, but work in tiff then save a jpg at the very end.
 

by Peter Ireland on Tue Jan 04, 2022 10:02 am
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Scott Fairbairn wrote:
Too much compression and too heavy handed sharpening will causes artifacts. Minimal compression, or none is optimal. If you work on a jpg image, as in doing image adjustments and save it with compression, then work on it again, then it increases artifacts because every time you save a jpg and compress it, you lose quality. I’m not sure if you do that in your work flow, but work in tiff then save a jpg at the very end.



Thanks, Scott.I always work in tiff,then resize for web once processing is complete using the maximum image size allowed for this site.I generally keep the size to 250k'ish, which is medium quality. Is this too low? What size do you save to?
 

by Scott Fairbairn on Tue Jan 04, 2022 11:21 am
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Peter Ireland wrote:
Scott Fairbairn wrote:
Too much compression and too heavy handed sharpening will causes artifacts. Minimal compression, or none is optimal. If you work on a jpg image, as in doing image adjustments and save it with compression, then work on it again, then it increases artifacts because every time you save a jpg and compress it, you lose quality. I’m not sure if you do that in your work flow, but work in tiff then save a jpg at the very end.



Thanks, Scott.I always work in tiff,then resize for web once processing is complete using the maximum image size allowed for this site.I generally keep the size to 250k'ish, which is medium quality. Is this too low? What size do you save to?



It does depend on the image too. Resizing to the dimensions I need, then keeping the quality slider as high as possible staying within the maximum file size allowed is what I do. Too much sharpening will create problems too.
 

by Peter Ireland on Tue Jan 04, 2022 5:32 pm
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Thanks again Scott. I thought the main problem with over sharpening were halo's,I didn't think it would cause the problems that you see in the image I posted?I realize each image is different, I guess I should just post higher quality images to curb the artefacts.
 

by Kim on Tue Jan 04, 2022 6:31 pm
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Make a copy of your tiff file with only capture sharpening applied, then resize to the site requirements and if you are using Photoshop apply sharpening via a smart filter, that will give you a second layer. turn off the eye on the bottom layer. Double click on the top layer on the right-hand end and bring up the Layer Style box then see the "blend if" box bottom right. there are two sets of sliders black to white, go to the top set and slide the triangle to the left until you see some gray check area appearing in the image then hold down ALT on PC and click on the triangle slider and it will split in two, slide apart to feather a little then close the box and turn the eye back on on the bottom layer. Turn the eye on and off on the top layer to see the result. This procedure gives you control over the sharpening so that only the mid-tones are sharpened thus eliminating the highlight artifacting along tree lines etc.

If it is still a little strong you can go back in and move the slider a little more if required.
 

by Peter Ireland on Wed Jan 05, 2022 10:36 am
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Kim wrote:
Make a copy of your tiff file with only capture sharpening applied, then resize to the site requirements and if you are using Photoshop apply sharpening via a smart filter, that will give you a second layer. turn off the eye on the bottom layer. Double click on the top layer on the right-hand end and bring up the Layer Style box then see the "blend if" box bottom right. there are two sets of sliders black to white, go to the top set and slide the triangle to the left until you see some gray check area appearing in the image then hold down ALT on PC and click on the triangle slider and it will split in two, slide apart to feather a little then close the box and turn the eye back on on the bottom layer. Turn the eye on and off on the top layer to see the result. This procedure gives you control over the sharpening so that only the mid-tones are sharpened thus eliminating the highlight artifacting along tree lines etc.

If it is still a little strong you can go back in and move the slider a little more if require


Thanks for this piece of advice, Kim.I have seen a few YouTube videos on blendif and the different scenarios it can be used for.It seems to be a useful tool to learn up on.
 I am finding if I just resize for the web without sharpening, I'm still getting the artefacts on the tree tops. So when I sharpen, of course this will make it look worse, but if the artefacts weren't there, it wouldn't be a problem. I'm sure a lot of posters don't have to do an extra step in their workflow to reduce the effect of JPEG compression, so what are they doing that I'm not, or are they posting larger file sizes up to the maximum size allowed on this forum? I'm probably making a mountain out of a mole hill, but I’m just curious to know.
 

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