Wikipedia:Reference desk/Archives/Computing/2019 January 15

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January 15

Blown-out file sizes

Why some video and image editing programs (including Movavi, Photoshop and free online programs) blow out the file size (compared to the original) even after you trim or crop a video or an image (which in theory reduces its file size)? My understanding is that, contrary to what some programs suggest during retouching, it's impossible to save the edited file in a higher quality that the original. Brandmeister^talk 19:04, 15 January 2019 (UTC)

I don't know the answer, but the same thing happens to me. Editing a file usually makes it larger. Maybe it has to do with compression. Bubba73 ^{You talkin' to me?} 19:12, 15 January 2019 (UTC)

Your assumption is not entirely correct.

First, you are mixing quality and file size. They are related, but not you have to consider compression. For example, what if I open a JPG image that was saved at 50% compression and I save it with 0% compression. My file will be much larger because it is using absolutely no compression. I won't increase the quality of the image. I get the image rendered from the 50% compression information. I save my rendered image with no compression. Did I increase quality? Not really. But, I did save more data, which takes more space.

Second, you mentioned editing a file. When you edit a file, you might increase the information required to represent the image. For example, I have an image that is completely one shade of red. That can compress down to a very tiny file. I edit it and write my name across it. Even if I crop the image, it takes more data to save the image that represents my name than it did to just say "it is all red." So, the image with smaller display size requires more disk space.

There are more issues to consider, but I thought those two would be enough to help you think about what exactly is happening. 216.59.42.36 (talk) 19:22, 15 January 2019 (UTC)