Why does simply saving a file quadruple the size? #1642
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Title says it all - help me understand what it is in simple processing that's making 12MB files into 48MB files. I have an image off my phone - JPG format. Native size is 12,737,008 bytes (13 MB on disk), 4500 × 8000, sRGB color profile. I cropped the top 1/3 of the photo, saved it (100% quality, because why wouldn't I) - and now it's 48MB on disk. I thought, OK, that's odd.... so I opened the image "fresh" (13MB source), made my crop, and this time saved as PNG. Same result - a 48MB file. Am I losing some sort of embedded compression in the "phone native" image? 
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Replies: 2 comments
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JPEG is a lossy compression format, but when saving at 100% quality I'd expect the file size to be similar to a lossless compression format like PNG. Saving at lower quality allows you to produce smaller file sizes, but eventually there may be noticeable artifacts It's very likely your original image was not saved at 100% quality, so I think you'd want to see if a lower value like 80 or 90% will give you smaller file sizes without producing noticeable issues |
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Thanks - that makes sense. |
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JPEG is a lossy compression format, but when saving at 100% quality I'd expect the file size to be similar to a lossless compression format like PNG. Saving at lower quality allows you to produce smaller file sizes, but eventually there may be noticeable artifacts
It's very likely your original image was not saved at 100% quality, so I think you'd want to see if a lower value like 80 or 90% will give you smaller file sizes without producing noticeable issues