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Author Topic: How to achieve this level of JPEG? Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 02-17-2016 10:42 PM                        There's a hell of a lot of JPEG going on in this picture: How is this possible, especially on a black and white image? I've tried saving the same image over and over and over and over and over and over and over at the lowest quality JPEG settings and I cannot achieve this ridiculous amount of JPEG. I see this a lot on Facebook. Facebook is a great site which has a cool replacement for this forum started by Mark Gulbrandsen that you should all visit. It's way easier to search and archive information there. LOL just kidding it's not. Anyway the Facebook pictures like this always seem to have maximum JPEG like this. I never see just minimum JPEG or moderate JPEG. I demand to know how this is accomplished.  |  IP: Logged Buck Wilson Jedi Master Film Handler Posts: 894 From: St. Joseph MO, USA Registered: Sep 2010 posted 02-18-2016 12:05 AM                     Download and repost times infinity? Or just pumping it through an NEC?  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 02-18-2016 12:31 AM                        Start with this: Compress to hell using Imagemagick or similar tools: convert -quality 1 good-jpeg.jpg bad-jpeg.jpg Get this result: Seriously, though, someone at Facebook presumably decided to make a high level of compression the default. Don't they have a size limit on uploaded image files, too?  |  IP: Logged Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 02-18-2016 02:28 AM                        Interesting. Your text is barely even readable any more. But the image I posted the text IS readable, it's just the outside of the objects that are riddled with artifacts. Maybe Photoshop (which I use exclusively) does not allow me to make JPEGs that bad. I don't think there are any unreasonable size limits for images on Facebook. They will recompress and resize if too big (well, they ALWAYS recompress). At least I assume they do. I'm not sure why they would recompress if the file size and pixel dimensions are already sufficient. I can understand them converting a 20,567 x 18,576 layered TIFF into a JPEG, but JPEG to JPEG seems pointless if it already matches the criteria.  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 02-18-2016 04:11 AM                     It looks like artifact on top of artifact. The original background was probably erased, poorly, then the picture was put through multiple resizings and resamplings. Most people just don't get it. Do they?  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 02-18-2016 06:00 AM                     I think it's easy to turn up JPEG artifacts when adding contrast to images compressed at low levels. Every JPEG Image contains these artifacts, but usually only on a level that is barely visible. Downscale it, increase the contrast, and these artifacts come out loud. - Carsten  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-18-2016 06:21 AM                     See now...as someone that actually did have to through ENES 101 (that is that first engineering class where things like drafting used to be taught and probably CAD is taught now)...I focused on what the idiot called a "bolt"...a proper engineer would call that a screw too (stop giggling)...a properly trained engineer knows that a "bolt" is a screw with the nut together. But I guess you guys focused on the crappy jpeg compression.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 02-18-2016 08:59 AM                    If you want some fun try putting unrelated images into each color channel.  |  IP: Logged Sean Weitzel Jedi Master Film Handler Posts: 619 From: Vacaville, CA (1790 miles west of Rockwall) Registered: Dec 1999 posted 02-18-2016 11:05 AM                     The facebook group was created by Jack Theakston. Mark is an admin and arguably the most prolific contributor.  |  IP: Logged Buck Wilson Jedi Master Film Handler Posts: 894 From: St. Joseph MO, USA Registered: Sep 2010 posted 02-18-2016 02:26 PM                     What's the group??  |  IP: Logged Sean Weitzel Jedi Master Film Handler Posts: 619 From: Vacaville, CA (1790 miles west of Rockwall) Registered: Dec 1999 posted 02-18-2016 03:57 PM                     I'm pretty sure Joe was referencing "Motion Picture Technology"  |  IP: Logged Bill Brandenstein Master Film Handler Posts: 413 From: Santa Clarita, CA Registered: Jul 2013 posted 02-18-2016 08:59 PM                     Joe, I'd agree with you that the software used to make the jpg will make a big difference, although in Photoshop if you turn the quality level down to "1," you ought to be able to get close. Especially if you do a slight resize, then do it again. Garbage like that happens on Facebook all the time - not only do they have to lower the jpg quality, but there's also a relatively low pixel count there as well. For example, the other day I posted an 8MB, 3456 x 5186 photo to FB, which now comes back as just 137KB and 1365 x 2048. That's pretty low compression quality!  |  IP: Logged Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 02-19-2016 03:17 AM                        I set the JPEG quality to ZERO in Photoshop and while it came back looking unacceptable, it was still about a trillion times better than Scott's example above. Even after multiple passes at level 0. I was using Scott's good image and recompressing it. I'm also wondering how they only get the outsides of things to get artifacts. Maybe they are applying a sharpening filter as well? Then over time the halo that generates get artifacts. That's my best guess.  |  IP: Logged Bobby Henderson "Ask me about Trajan." Posts: 10973 From: Lawton, OK, USA Registered: Apr 2001 posted 02-19-2016 09:23 AM                     quote: Joe Redifer How is this possible, especially on a black and white image? Really severe lossy JPEG compression would never yield an image like this in just one pass. That's impossible. The image degradation from lossy compression would take place on a global basis, affecting everything in the image fairly equally. The image above is the combination of a low quality background image with higher quality type and objects laid on top of it. The look of this image might have been done on purpose. Some people like creating grungy looking artwork, but normally the "stressed" textures come from more natural looking sources. You could take a layered Photoshop image with the objects and words floated above a background with the glowy effects. Export that background as separate image, resize it pretty small and lossy compress the living hell out of it. Re-open the image and resize it back up to its original size, but using "nearest neighbor" for the re-sampling mode to make the pixels huge like an Atari 2600 game console. Then re-save the JPEG image a couple more times to bake even more lossy compression pollution into the image. Re-open the image and copy/paste it into a layer of your original Photoshop file. You'll have clean looking objects floating above a really shitty looking layer. Export the whole thing as a badly compressed JPEG image.  |  IP: Logged Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 02-20-2016 12:41 PM                        quote: Steve Guttag I focused on what the idiot called a "bolt"...a proper engineer would call that a screw too Your entire education is wrong. A screw is loosened/tightened with a tool that penetrates it. Something that slides or pokes into it. A bolt is loosened/tightened with a wrench. How does it feel to be so wrong? That's a legitimate question, as I've never been wrong.  |  IP: Logged

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