Timeline for How to convert JPEG to RAW in Photoshop or similar?
Current License: CC BY-SA 3.0
14 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 6, 2016 at 1:04 | comment | added | le3th4x0rbot | @JamesSnell There are other causes of artifacts in rendered raw images, such as when colors are interpolated from the sensor intensity values using the mosaic filter pattern. | |
| Feb 6, 2016 at 1:02 | comment | added | le3th4x0rbot | @JanDvorak Lossless JPEG uses a predictive coding model, unlike regular JPEG files which use a discrete cosine transform. It really should provide pixel identical images. | |
| Feb 6, 2016 at 0:51 | comment | added | le3th4x0rbot | One reason for RAW files in competition is to prevent most photo shopping. | |
| Feb 5, 2016 at 21:37 | comment | added | Chris H | @JanDvorak the normal jpeg algorithm can't be guaranteed lossless. The lossless algorithm isn't the normal algorithm. Rounding errors are a separate issue and more related to the image processing than the file/data format. | |
| Feb 5, 2016 at 20:24 | comment | added | James Snell | @PeterM - not in comments, though it sounds like a good basis for a question. | |
| Feb 5, 2016 at 17:44 | comment | added | John Dvorak | @ChrisH well, you've got rounding errors, which might pass as "mathematically lossless", but also you've got the quality settings. JPEG is only mathematically lossless if you use the highest settings, but then the file size blows up by several orders of magnitude as the only regularity usable for compression are rounding errors. | |
| Feb 5, 2016 at 17:31 | comment | added | Peter M | @JamesSnell Can you point me to a list of Nikon (and Cannon) cameras vs lossy/losseless RAW formats? While I'm not about to go buy a new camera based on ZOMG the RAW is lossy!!!! I'm curious to see what the cutoff points for the formats are | |
| Feb 5, 2016 at 16:03 | comment | added | user | For more on the third bullet point, consider Why is giving clients RAW files such a sensitive matter among photographers? | |
| Feb 5, 2016 at 15:35 | comment | added | Chris H | @JamesSnell lossless jpeg is mathematically lossless (wikipedia in case you're interested). CR2 also stores previews in lossy jpg. | |
| Feb 5, 2016 at 13:43 | comment | added | James Snell | @ChrisH - Nikon has multiple raw options, though only the lossy compression is the only option available in the lower-end cameras. The artefacts are really something that only pop up if you start pixel-peeping and only under certain conditions. CR2 has similar problems as it also stores the main image data as a jpeg (source: lclevy.free.fr/cr2) and while it's labelled 'lossless jpeg' I very much doubt that it really is. | |
| Feb 5, 2016 at 10:09 | comment | added | Chris H | @JamesSnell I'm sure there's a lot of copy-pasting of rules though up by someone who thought they knew what they were doing. My interperetation may not be perfect. I must confess though, I don't get Nikon's RAW if it has compression artefacts -- what's the point of it? Canon's CR2 uses lossless compression and the only Nikon SLRs I've used were 35mm | |
| Feb 5, 2016 at 9:49 | comment | added | James Snell | Actually, as someone who has run competitions like this, a good chunk of that is good evidence of how little those in the 'competition'/club scene actually know about what they're doing... Raw on the D3200 certainly does suffer compression artefacts. The main reason for the raw request is (a) to prevent cheating and (b) to ensure only global modifications have occurred in photojournalism events. I suspect if you contact the organisers and say you shot in JPEG they wouldn't have a problem with the entry, certainly won't hurt to ask. | |
| Feb 5, 2016 at 9:41 | comment | added | zackygaurav | This is nearly perfect answer from a competition point of view. Thank you Chris H | |
| Feb 5, 2016 at 8:59 | history | answered | Chris H | CC BY-SA 3.0 |