Implemented Feature suggest, save as previous jpeg quality setting

[cambys]

the new version of GIMP has a setting under save as jpeg that allows you to check "use quality settings from original image" this reads the jpeg quality setting used in the file and saves the new file in the same setting, this should reduce compression errors while keeping file size as small as possible

[Artful]

jpg batch rotate with same quality

Just found this (among many related threads) while trying to batch rotate jpgs (no orientation tagging by the camera), having discovered the resulting change in file size. The batch dialog only offers manual setting of "Save quality", so I'm going for 100% and using more disk. More sensible would be a lossless rotation, but that facility, enabled by the downloaded optional Jpg_transform.dll plug-in, doesn't seem to be batchable, and trims off the remainder of edge pixel count / 16. Maybe I should get out more.

[hayash]

Save jpg at previous compression rate

I often batch process files from multiple sources. (E.g. multiple digital cameras.) The issue right now is I'd like to keep the file as small as possible without losing quality. If a “save as original compression” feature is added for batch processing that would be great.

That said, also I come across another need for an add-on to the above feature. If you could specify to use the original compression level if the original compression is lower than a compression level that is specified in IV.

For instance.

Start with:
image_a.jpg compression = 95%
image_b.jpg compression = 80%

Batch process both images at 90% compression.

End up with:
image_a.jpg compression = 90%
image_b.jpg compression = 80% (untouched)

That way the images that are of higher compression (I.e. lower percentage and lower quality.) to begin with will not get bloated after processing.

This would definitely help, since many batch processing job have images of varying compression rates.

[Skippybox]

Use FastStone or XnView.

[Bhikkhu Pesala]

I got a reply from Irfan on this feature request:

JPG: no, there is no really secure way to detect last used quality, not easy/fast at least.

Note: even if you know the quality, JPG is always lossless, if you save it 5 times with 75%, you will lose 5 times quality. Even with 100%, JPG is lossy.

=> doesn't really makes sense for JPG.

The user can set the save file size, using RIOT plugin, this is similar.

[Mij]

Even though what Irfan says is undoubtedly true it is not all that helpful to those who worry about loss of quality when saving jpegs. The fully integrated features of Faststone Image Viewer are much easier to use than the combination of IrfanView and the Riot plug-in. Faststone makes an estimate of original quality and by default saves at that same value. The options allow you to adjust that value and see what the resulting file size will be. It also allows you to view and compare the original and proposed save images.

This does seem to be an area where IrfanView is lagging behind the pack.

[hayash]

FastStone.

Which FastStone product do you recommend?

I've seen four different applications.

Image Viewer
Capture
MaxView
Photo Resizer

It looks like Image Viewer, MaxView, and Photo Resizer may have this capability, since that all can resize the image.

Also I guess the programming needed to do this work is great, so is that the reason for not wanting to add this functionality in IV?

Thanks for the feedback!

[Bhikkhu Pesala]

FastStone Capture is extremely useful for taking screen shots. It can also open JPG images from disk and save them with the last used compression estimated on the save as options dialogue.

Launch it on Windows Startup and open it from the System Tray whenever you need it, or use the PrintScreen shortcuts to grab screen shots.

[hayash]

Thanks.

Thanks for all of the help. I'll take a closer look at the FastStone products for this functionality.

Seems like Irfan really does not think that this functionality is too useful. In any case IrfanView is still an outstanding application. Thanks to all for your time and help!

[Skippybox]

All the Faststone products are great, as well as XnView. Each has benefits and weaknesses. It really depends on what your application is. You may want them all, or only need the one.

All the FastStone software comes as either an installed program or a portable version. At this point, MaxView and Capture have become shareware, but you can find there freeware versions here:

Capture 5.3
MaxView 2.1

FastStone Image Viewer is a fully-featured image viewer
MaxView is a lite image viewer
Capture is for screenshots and some editing
Photo Resizer is a batch conversion program

FastStone Image Viewer contains basically all the capabilities of the other three programs plus more. However, you may like operating the smaller program for your particular task.

XnView is also a fully-featured image viewer

[luciansabo]

batch for lossless transformation would be nice.

getting the quality value used is:
1) not very precise
2) not so useful

Not just quality affects jpeg compression. A very important role has chroma subsampling. So a program must detect this also. IV does not let you choose chroma. Only disabled or default is allowed (I don't know what is using - maybe 4:2:2 or 4:2:0)

On the other hand even if you get the chroma and quality used, saving with the same values results in further image degradation. JPEG loses quality on each compression.
So the resulting image will be more ugly if you choose the last settings.

If you want to keep quality, and you don't need an exact similarity save it as q90 with no chroma.
If you care about similarity use a program like RIOT.
If you really care about image quality don't use JPEG !

[Skippybox]

JPG Lossless Transformations can be done in batch if you select several JPG files from Thumbnail window. Of course, they must meet the requirements for a successful lossless operation, otherwise it won't be lossless.

[luciansabo]

Completelly forgotten about this feature. I've used it a long time ago...

[hayash]

Very helpful feedback.

I will try them all and see which works best for the work I need done.

Thank you all again!

[hayash]

Very helpful feedback.

I will try them all and see which works best for the work I need done.

Thank you all again!