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I have some jpg images exported from RAW files using UFRaw and they are very large in size(>15MB). So, in order to save space, I opened them in GIMP and re-exported as tif images with JPEG compression and the results were very good, file sizes reduced to about 5MB.
But since the tif images were exported using GIMP, there were no exif data like Camera Maker, Date taken etc.

I, then, manually added some exif data, this is where things get weird, the file size increase about 5 times the untagged file.

Eg: This is the file size of the original tif image, no exif data added: OriginalImage

This when Camera Maker is added:
enter image description here

And when Date Taken is added:
enter image description here

Why is there such a huge increase in the file size?
Is there any way to add exif data without increasing the file size?

  • Is there a reason that you save files as .tif? – Zenit May 12 '17 at 8:06
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    You are applying lossy compression twice. Never recommended. I think you should reevaluate your workflow. – osullic May 12 '17 at 8:07
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    No, you couldn't. TIF with jpeg compression is just a container for a jpeg-file. You could easily save your image as jpeg with the same (and ever a bit smaller) file size and equal quality. – Zenit May 12 '17 at 8:47
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    TIF compression might be lossless, yes. But you save you files with JPEG-compression and jpeg is not losless. – Zenit May 12 '17 at 8:48
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    TIFF is a container format, like a ZIP file, with multiple pages. It is a rather complex format. – Thorbjørn Ravn Andersen May 12 '17 at 9:24
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I don't know how you added the exif data, but it could very well be that the application you used for this recompressed the file, and not with jpeg compression. Windows explorer recompresses a jpeg-tiff as LZW if you edit the metadata, you can see that in the file properties/details tab.

Anyway, if you don't like the size of a jpeg exported from a raw file, the proper way is to export it again, but with a lower quality setting (be aware of possibly visually apparent loss of quality, maybe make some A/B tests to find a good compromise between size and quality.).

The reduction in file size is not from the jpeg->tiff conversion, but because gimp apparently applied a stronger compression, but you can change that directly at the source (UFRaw), too.

  • I used the native Windows Explorer to edit the metadata. – RogUE May 12 '17 at 8:57

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