Requested request: better chroma subsampling control on jpeg

[_ck_]

Hi, would it be possible in a future version, instead of just medium (4:2:0 default) and OFF (disable) could we get the full:

high 4:1:1
medium 4:2:0 (default I believe)
low 4:2:2 (makes smaller files but no distortions on text)
off 4:4:4

For jpg with text on a solid background, the default 4:2:0 makes distortions, and OFF makes the file too large.

I know I can change this via RIOT or other programs but for batch operations it cannot be done.

Thanks for considering!

[quatermass]

This is a good idea. I can do this subsampling via GIMP for Windows if I need to. But it would be great if Irfanview could do it.

It makes a huge difference when you've got cartoon like imagery to jpg. ie text, lines, screenshots, etc.

[MItaly]

It makes a huge difference when you've got cartoon like imagery to jpg. ie text, lines, screenshots, etc.

In these cases isn't it better to use PNG?

[quatermass]

In these cases isn't it better to use PNG?

Yes. But jpeg still makes for much smaller files.
An ~400x400 jpeg could be ~25K, a typical PNG may be ~200K.

Also a PNG may take longer to render on a web page.

But there are social aspects too.
You'd also be surprised at how most ordinary users don't know what PNG is and why or when they should use it. As I'm a IT administrator I've learned that jpeg is 'King' as far as users are concerned. Probably due to digital cameras, etc.

Still, its a step up from ten years ago when people would render real-world scenes using GIF!

[Bhikkhu Pesala]

Yes. But jpeg still makes for much smaller files.
An ~400x400 jpeg could be ~25K, a typical PNG may be ~200K.

This simply isn't true. For photographic images, JPG will nearly always be smaller than PNG, but for cartoons, line drawings, and screenshots (dialogues etc.), PNG wins hands down. It is always sharper, and nearly always smaller, often significantly smaller than JPG. Further savings in file size can be made by colour reduction with minimal loss of quality.

A Sample Dialogue (Save as a JPG at a medium quality setting of 75, then compare size and quality with PNG.

The attachment is further optimised with pngcrush reducing this 859 x 583 pixel image from 38 K to 35 K. Cartoon images will also have few colours, or large areas of the same colour, so will compress well to PNG. Screenshots with photos in the background will usually be smaller if saved in JPG format, but dialogues, menus, and toolbars have fewer colours.

[quatermass]

This simply isn't true. For photographic images, JPG will nearly always be smaller than PNG, but for cartoons, line drawings, and screenshots (dialogues etc.), PNG wins hands down. It is always sharper, and nearly always smaller, often significantly smaller than JPG. Further savings in file size can be made by colour reduction with minimal loss of quality.

Yes, but only if the image contains a significant amount of cartoon like imagery.
What about a real-life image with a text headline say?
These are commonly ten times bigger as PNG than jpeg.

You and I may know what the benefits of PNG are over jpeg but the average joe doesn't.
My users look at the PNG plugin for Irfanview which you can optionally use if you want to squeeze out some extra shrinkage and a look of horror comes over them.

I still get 3D designers sending me 600dpi jpeg images of their latest designs and they're so full of dirt (artefacts around edges) I can't use it. I repeatingly try to tell them about PNG and TIFF and I really shouldn't be doing this for £50,000+ paid graphic designers!

Such is the real-world.

Nice chatting with you.

[MItaly]

I managed to make my mother understand when PNG/GIF is better than JPEG, I can't believe that a 3D designer can't understand it. If they are really stupid just smash their head over the desk every time they send you a JPEG; they will learn quickly.
BTW, if they find difficult just to save in JPEG, wouldn't they become mad if they had to think about chroma subsampling?

[quatermass]

I managed to make my mother understand when PNG/GIF is better than JPEG, I can't believe that a 3D designer can't understand it. If they are really stupid just smash their head over the desk every time they send you a JPEG; they will learn quickly.
BTW, if they find difficult just to save in JPEG, wouldn't they become mad if they had to think about chroma subsampling?

Males don't like to ask for directions, male engineers don't listen to IT bods.

wouldn't they become mad if they had to think about chroma subsampling?

Hehe. Probably.
But it's like FAQs, they really exist so we IT bods can point to them and say - "there I told you so", cause people rarely read them.