Rotating in batch convert makes file very big

[MrSupremeOverlord]

And when I rotate the jpg files using the Rotate 90 degree button, file size remains the same. Can I achieve that with batch convert as well?

I tried turning on and off:
use jpeg 2
progressive
optimize huffman table
subsampling settings
use estimated quality
preserve meta data

(Quality has always been set on 100%)

[cday]

If you haven't already done so, you might look at the properties of one of your images open in the viewer: Image > Properties... or the 'i' icon on the toolbar.

Off the immediate topic, do you actually need JPEG quality set to 100, that is very rarely needed and usually substantially increases file size: usually 90% or quite possibly 80% results in an image for most practical purposes indistinguishable from the original file, but that's really another topic discussed elsewhere on the forum...

[MrSupremeOverlord]

And then look at the estimated quality?
Why doesn't the use estimated quality overrule the set quality?

[user0]

when I rotate the jpg files using the Rotate 90 degree button, file size remains the same.

you used lossless rotation, it is not available in Batch convert

[cday]

And then look at the estimated quality?

Yes, among other properties that might be relevant, but also note the full Write settings text 'Use estimated quality (when possible)'.

If you can provide an example file, someone possibly more knowledgeable than me might be able to have a closer look, the forum attachment size limit 2MiB, otherwise using a download link.

you used lossless rotation, it is not available in Batch convert

So do your images actually require lossless rotate?

[jkm]

(Quality has always been set on 100%)

You're recompressing the file. And Quality=100 makes files bigger.



Even though jpeg is "lossy", taking an image compressed with quality=70 and recompressing with quality=100 will make the file bigger, not smaller.

If you want to rotate without recompressing the files, don't use Batch Convert for the rotation.

Instead, select the files, and use Metadata->Lossless transformations. That will do all your rotations without increasing the file size.