quality resizing

[tomchook]

Hello,
When I resize a picture (for example to 20% of original size) the outcome is not as good as the original picture. It looks like "sharpen" filter was apply on it, and it's too pixelated. On the saving option of the jpeg I have it on maximum quality (100) and I checked the "disable color subsampling".

What should I do?

[Bhikkhu Pesala]

There is an option on the resize dialogue to apply sharpen after resizing.

Try disabling that or try using different filters. Lanczos may not always give the best results.

I am not at all surprised that an image resized to 20% is not as good as the original, and pixelated. There is not nearly as much data in the file — the original contains 25 times more pixels, so it is sure to look much better.

[tomchook]

these are my settings


I didn't apply any filters, so it shouldn't look sharpened..

The same picture that i resize in the same ratio in photoshop looks a lot better. So how come?

[Laurent]

Hi tomchook,

Bhikkhu Pesala is speaking of these settings:


Laurent

[tomchook]

my settings are just as yours. here is how it looks:


what else can i do to imporve the quality? (actually what i want is not to loose the quality, which means that the picture will be smaller, as if i zoomed out, like in Windows Picture and Fax Viewer)

[matera]

In the "Resample filter" dropdown of the resizing dialog, try some different selections. The B-Spline might give you better results, it makes things smoother.

[Sam_Zen]

I think in the process of remaining quality while resizing, the option to 'sharpen after resizing' is a wrong one.
The sharpening should be done before resizing. It may produce pixel-artifacts, but a part of it will
be lost again after the resizing formula anyway.

Whether it is necessary to sharpen the resize-result afterwards also is dependent of the situation.

Another aspect : Resizing (Resampling I like to name it) to 20 % in one take is quite a rough method.
Better divide this during some inter-steps in the process.
So first resize to 80 %, optimize the picture again, and resize again to a smaller dimension.
It takes more work, but if you want to remain quality, that's the price.