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I made some small edits on a JPG in IrfanView (cropping and color corrections), and want to save it without losing any quality, but would rather not save as a PNG as it doubles the size. If I save it as a JPG with quality set at 100%, is that the best way to do it?

I will be printing the files as large as possible so it's important that the image quality stays as high as possible, but at the same time I cannot have PNG files, they take too much space.

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    Could you explain why PNG files take too much space? Are you dealing with some storage/bandwidth/data limits? – osullic May 18 '18 at 19:30
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If you want to save it without losing any quality, then the only way to do it is to save using a lossless image file format.

Realistically though, if you edit a JPEG file just once, and re-save as JPEG with 100% quality, then to your eyes, you will almost surely never perceive any quality loss.

I would like to also point you to some advice on impulseadventure.com about resaving images, the summary of which is that results "can be adequate if the compression algorithm is the same (ie. same quantization tables & quality settings)":
https://www.impulseadventure.com/photo/jpeg-compression.html#resaving

  • Thanks. I forgot to mentions that I will be printing the files as large as possible so it's important that the image quality stays as high as possible, but at the same time I cannot have PNG files, they take too much space. – larry909 May 18 '18 at 14:14
  • @osulic So would your answer change? – larry909 May 18 '18 at 19:15
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If I save it as a JPG with quality set at 100%, is that the best way to do it?

No...Yes, well... It depends.

Let's get a bit technical, but not much.

IrfanView uses a specific subtype of JPG compression called 4:2:2 that has lower quality over PhotoShop or PhotoPaint one that has a 4:4:4 one.

So if you started with a really high-quality JPG image you will lose information even at 100% quality settings.

The analysis is here.

Take an uncompressed image and put it over the already compressed one with blend mode difference.

enter image description here

Then use levels to increase the contrast on the image.

Here is a comparison between Irfanview at max quality vs a generic one (Gimp, PhotoPaint, Photoshop gives similar results)

enter image description here


Yes.

If your image had already some 4:2:2 compression, some compression blocks are already formed, so setting it to 100% will probably re-use those blocks.

No.

A problem here is that a crop on the top or left side of the image can force the JPG algorithm to prepare some new compression blocks over the previously existing ones.

Yes.

If you do not mind, and you can not see the diference, its ok.

No.

If your target is to have a better ratio of compression, you can compress it more. Try 90%. I would not consider an IrfanView edit a "professional Edit, just a casual one so it does not matter.

No.

One more thing... If it is for print... why do you care about a heavier file? You need to try to maintain overall quality. So if it is for digital print, use PNG. If the file was CMYK use TIF.


IrfanView has a good quality compression. If you do not mind, the little loss of information, it is ok. Especially for batch crops.

  • "why do you care about a heavier file?" Because I have hundreds of files that need to be uploaded and transfered individually to a selling website and they originally were created in jpeg format but need to be cropped and re-saved. – larry909 May 24 '18 at 0:17

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