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Dear all, I would like to compress my massive amount of JPGs  in order to save some space and when I just opened up a picture in order to try out the amount of compression that would not yet show too much in the quality the following thing surprised me:

The original JPG is about 4.4 MB big. If I go straight to "Export" (really don't do anything in between) and want to export it at 100% it is suddenly 9.43 MB when using Affinity Photo. When using Photo Plus X8 the "new" picture is about 8.0 MB. So it more than doubles in size just by opening in a programme and exporting it in the original format, the original resolution and at the original quality?

Is it correct to assume that this is somehow because of the Resampling Method? Kind of like: I didn't do anything but the programme actually did quite a lot?

And if I cannot export without resampling: Can anyone recommend a combination of Resampling Method and quality level that one the one hand don't lover the perceived quality too much but on the other hand put a good dent in the file size?

Thank you very much in advance,

Dreamer

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Resampling method should not affect any if you do not change the pixel dimensions of the image. That is not the problem.

I suppose your original JPEGs were saved not with best quality, but with some optimized quality setting. AP default on the other hand is very best 100% quality. That is why your saves are bigger.

My opinion is that it is not worth the effort to recompress JPEGs just for space saves. External hard drive or some cloud solution would be better.

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Hi Fixx,

First of all thank you for replying to my question. But there's something in your answer I don't quite understand: If my JPEGs were originally not saved with the very best 100% quality, than Affinity could not save them with better quality unless it actively did something - could it? (And I swear I didn't change anything myself. I went straight from opening the pic to exporting it.)

But I am not worrying about harddrive space. I want to back up my stuff not just on external drives and discs but also in a cloud - but I don't worry about cloud space, either: It's the internet connection. Where I live, the best I can get is ... not the best that would be possible. It's okay, I can watch youtube videos, but when it comes to uploading I am grateful for every GB I do not have to upload. Very, very grateful.

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1 hour ago, Dreamer said:

 

First of all thank you for replying to my question. But there's something in your answer I don't quite understand: If my JPEGs were originally not saved with the very best 100% quality, than Affinity could not save them with better quality unless it actively did something - could it? (And I swear I didn't change anything myself. I went straight from opening the pic to exporting it.)

Think of it this way: you open a photo, and save it as JPEG with some quality lower than "best". This results in some lossy compression, a small file size, and an image which approximates the original. Call the original #1 and the saved, lower quality, smaller copy #2.

 

Starting with #2, as you may be doing, you can never recovery what was lost and get back to the quality present in #1.

 

Now you want to save a copy of #2, giving #3.

 

You can save it with lower than "best" quality, and get a file smaller than #2, and which only approximates #2. 

 

Or, you could save #3 with best quality, and more exactly match #2. But in trying to more exactly match #2 you could end up with a file larger than #2.

 

Affinity is simply trying to create an output file that matches what's on your screen, and the fact that what is on the screen only approximately matches #2 isn't really relevant. Once you opened #2 you ended up with a file with a certain pixel dimension, no matter the quality of those pixels. It's the quantity of them, and the faithfulness (quality) of preservation that will determine the file size on disk.


-- Walt

Windows 10 Home, version 1909 (183623.476),
   Desktop: 16GB memory, Intel Core i7-6700K @ 4.00GHz, GeForce GTX 970
   Laptop:  8GB memory, Intel Core i7-3625QM @ 2.30GHz, Intel HD Graphics 4000 or NVIDIA GeForce GT 630M
Affinity Photo 1.8.3.641 and 1.8.4.650 Beta   / Affinity Designer 1.8.3.641 and 1.8.4.650 Beta  / Affinity Publisher 1.8.3.641 and 1.8.4.651 Beta.

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