Timeline for Two EXACTLY the same .jpg images with one image more than twice the file size of the other - Why?
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Jun 23, 2021 at 22:41 | comment | added | Peter Cordes | JPEG does its lossy quantization in the frequency domain, not spatial, so spending the same number of bits to encode the chroma can give roughly similar quality whether that's spread over 4x as many pixels (4:2:0 subsampling) or not. It's not quite that simple (e.g. at lower chroma rez, important details are spread over fewer pixels and thus have higher spatial frequency within a DCT block), and "quality" settings may not bias the quantization according to how much the chroma was subsampled. But just like with video, 4x the pixels doesn't mean 4x the bits, if you hold visual quality const. | |
| S Jun 23, 2021 at 14:17 | history | suggested | Matt Dunn | CC BY-SA 4.0 |
Fixed spelling mistakes, and improved footnote formatting
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| Jun 23, 2021 at 13:40 | review | Suggested edits | |||
| S Jun 23, 2021 at 14:17 | |||||
| Jun 23, 2021 at 7:32 | history | edited | xenoid | CC BY-SA 4.0 |
added 51 characters in body
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| Jun 23, 2021 at 6:59 | history | edited | xenoid | CC BY-SA 4.0 |
added 41 characters in body
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| Jun 23, 2021 at 6:48 | history | answered | xenoid | CC BY-SA 4.0 |