Touching files

imagladry

Posts: 23

10 months ago

I seem to have a series of not-destructiveoperation that, at least sometimes, alter open, but unchanged files.

I have a long list of jpg files in the Finder. They are currently sorted by size to ensure a semi-random nature. I do the following operations on the files: Open, Select All, Copy, Close.

Even though none of those operations alter the file, I still get a background saveoccurring. Becuase of the fluid nature of jpg's the size of the file changes, thereby messing up my order.


It is my understanding that is there are no destructive operationsdone to the image/file, then the file in the Finder should not change. Am I wrong?





Help.






If you have a hard time duplicating the problem with a single file, try it with a set of fifteen files. That is the file set size I am using.
Sebastiaan

Posts: 3492

10 months ago

I hope I understand your qestion correctly.

From what I understand from your question is that you open jpg-files in Pixelmator and as you look at the file size when closing the files or closing pixelmatoror when saving the file you'll see that the size of the file changes.

By default the jpg-file is lossy. This means that with every safe image information gets lost. Even if you don't do any destructive work on your document or any work at all. Every time you safe back to a jpg-file there will be information thrown away to save file size.

If you are working on jpg files, you should change the format to the standard Pixelmator file format (PXM) or use any other lossless image format like PSD and TIFF for example. Once you feel your image is ready then it's time to think lossy and safe your image into a format that saves disk space.

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