What's happening to my images?
March 24, 2015 6:24 AM   Subscribe

Hoping someone can help. Why are my images fine on my computer, but full of artifacts when uploaded?

Using Photoshop Creative Cloud 2014, I'm editing a series of images out from RAW files (using Adobe Camera Raw to PS CC) and having some issues with artifacts in the uploaded images. On my hard drive, or viewing them in PS/LR/any other software, they look fine; when uploaded to Flickr they are clearly full of artifacts (see the bottom left and top right). (Warning: images contain one, small snake.)

What am I doing wrong? Workflow goes like this: Open image in ACR -> make any changes required -> open image in PS CC -> sharpen (either High Pass sharpening or a custom PS action) -> crop -> paint layer mask over subject -> use Curves tool to select white point in one of the corners of the image -> make any further changes in contrast using Curves tool -> flatten and save as JPG. Working in a 16 bit space, if that matters.

I don't understand why the photos display fine in PS or in preview locally but look this bad when uploaded (anywhere - I tried using Tumblr to upload as well, but Tumblr also uses some image compression on locally uploaded files).
posted by Nyx to Technology (8 answers total) 1 user marked this as a favorite
Can you give more description on what artifacts you are seeing?

I don't see any artifacts, and your two imgur links are to the same picture (fine vs clearly full of artifacts). There is a second imgur picture to click to once on imgur but it looks the same to me except with a half cropped out drop shadow border.
posted by TheAdamist at 6:46 AM on March 24, 2015

flatten and save as JPG

Just checking the obvious, what is the compression level you're using when you save as JPGs? You're checking them on your desktop after you save as JPG, correct? And you've checked in multiple browsers? (there was a Chrome bug a while back just for example now fixed). And downloaded the largest size on Flickr to check it?

I can see the artifacts, just sort of a slightly darker blobby smudge in a slightly yellower white in upper right and lower left. That is what you are talking about?
posted by jessamyn at 6:48 AM on March 24, 2015

Best answer: Ok, I cannot see the artifacts either.. but I pulled both images into photoshop and magic wanded the white sections with almost 0 tolerance (so it picks up just white and the very-slightly-completely-indistinguishable-from-white not white)

In both images, you have some very slightly not white areas that are darker then my tolerance. They're in the same areas as where you describe seeing the artifacts. What is interesting is that when saved as a jpg, it blends the not white enough with the white that my tolerance picked up more pixels in it's selection. It's likely that your eyes and monitor are better then mine, and thus you're seeing the artifacts where I can't. You're not going crazy though, there are slightly darker sections in those corners.

Something you might try.. magic wand the raw image just after it's flattened. Try a tolerance of 10. In my photoshop, this selects all the white around the snake except for him and his shadow*. Inverse the selection and delete it/fill it with complete white (#FFFFFF). Save as jpg and upload to flickr and see if you still see the artifacts.

*because the snake is white, I would also Select > Modify > Expand the selection by 30-50 pixels or so, just so you make sure you get the very top and left parts of him
posted by royalsong at 7:22 AM on March 24, 2015

The two Imgur links you sent appear to be the same link. The only difference in the URLs is that one has a #0 at the end. I compared those two images using Kaleidoscope and they were identical.

(I didn't try to compare the flickr image because it's a different size.)
posted by alms at 7:50 AM on March 24, 2015

I can see what you are talking about, I think, on my good monitor. It looks like jpeg compression if I turn the brightness all the way down in photoshop. I'm not sure if flickr and imgur compress your images upon upload, or if you aren't saving them at a high enough quality. You may try masking more carefully, as in the snake image it looks like you intended the background to be 100% white but the top right and bottom are just ever so slightly off, and the compression may make that visible.
posted by polywomp at 7:51 AM on March 24, 2015

Response by poster: Arrgh, sorry about the imgur links - I was posting in a hurry before work. The artifacts I'm seeing are dark, pixellated banding in the bottom left corner and upper right corner - something like you'd see in a low-quality JPG.

Yes, I am saving at full quality, as high as Photoshop will go. I think the answer is just going over it more carefully to make sure EVERYTHING is white in the background, but I'm still puzzled as to why the images look fine on my computer but are so badly banded when uploaded to the internet. Local display settings? (Monitor is set to 1920 x 1080, 60 Hz, 32 bit colour.)
posted by Nyx at 9:34 AM on March 24, 2015

It's probably a combination of monitor + browser and maybe whatever flickr does to process images. Does it look different on your phone/work computer/tablet/laptop?

My friend recently had problems with a gif displaying weird artifacts that could only be seen on her work computer on IE.
posted by royalsong at 10:08 AM on March 24, 2015

To eliminate the web browser software as the source of the difference, you can open the local image in your web browser (drag it into your browser window). If that still looks the same then I would suspect Flickr processing as the issue.

You could also compare how the image appears when uploaded to different services. For example if it is shared in your public Dropbox folder then your browser should download the original without any other processing applied.
posted by Gomez_in_the_South at 7:09 PM on March 24, 2015

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