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Downscaling resampling tutorial

PostPosted: Fri Feb 17, 2012 4:37 pm
by Cage
Hello, just a little bit of (maybe) useful info, if you're scaling down textures. For Photoshop, might be translatable to other software.

Here's my texture I've picked up on http://www.texturemate.com/
Image

Liked the colours and details. Let's make a Doom texture out of it! We can use the full texture, it doesn't need croping. 3888x2592 is a bit too much for our needs so let's scale it down.

Image

I've highlighted the resampling droplist. Here are the results:

Image
Nearest neighbor
Whoever scaled down photo textures for use in oldschool stuff like Duke/Doom/whatever, probably tried using this resampling method since.. it's not doing any resampling. While it should work in theory, with things looking nice and pixelly, the end result is just too rough and details start to look like noise.

Image
Bicubic. Oooh, smooth. Too smooth. Almost being blurry :P It's like the opposite of the above result - instead of being noisy it's blurry.

Image
Bicubic sharper. OH GOD PLEASE NO. The result looks like the above bicubic result but with ugly SHARPEN filter aplied. NO.

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Bilinear. It's - it's smooth while a bit better at preserving the details than bicubic. I think it's the best solution for scaling down textures to oldschool sizes ;) While you're difference may be subtle for you, non-graphic-nerds, it just feels right in my opinion.

After making it tileable and some tablet and brush tool voodoo you can get something like this:
Image

Cheers and hope this helps in anyway.

GIMP:

ETTiNGRiNDER wrote:Just did a quick poke around with GIMP, which, disregarding "None", has "Linear" "Cubic" and "Sinc". Sinc appeared to have the best effect, but oddly, Linear and Cubic seemed to have reversed effects from what you had with Photoshop (Linear was the blurry one and Cubic was better looking).

Thanks!

Re: Downscaling resampling tutorial

PostPosted: Fri Feb 17, 2012 4:50 pm
by Tormentor667
Awesome :)

Re: Downscaling resampling tutorial

PostPosted: Fri Feb 17, 2012 6:04 pm
by ETTiNGRiNDER
Cage wrote:For Photoshop, might be translatable to other software.

Just did a quick poke around with GIMP, which, disregarding "None", has "Linear" "Cubic" and "Sinc". Sinc appeared to have the best effect, but oddly, Linear and Cubic seemed to have reversed effects from what you had with Photoshop (Linear was the blurry one and Cubic was better looking).

Re: Downscaling resampling tutorial

PostPosted: Fri Feb 17, 2012 6:36 pm
by Cage
ETTiNGRiNDER wrote:
Cage wrote:For Photoshop, might be translatable to other software.

Just did a quick poke around with GIMP, which, disregarding "None", has "Linear" "Cubic" and "Sinc". Sinc appeared to have the best effect, but oddly, Linear and Cubic seemed to have reversed effects from what you had with Photoshop (Linear was the blurry one and Cubic was better looking).


Since a lot of people here use Gimp (or seems so) I've added that to the first post. Thanks!

Re: Downscaling resampling tutorial

PostPosted: Fri Feb 17, 2012 6:49 pm
by Enjay
The options in Paint Shop Pro:

Image

"Smart size", I think, just seems to pick bilinear if the image is 24 bit or greyscale and pixel if it is 256 colours or less. Pixel resize does no filtering/resampling.

Re: Downscaling resampling tutorial

PostPosted: Fri Feb 17, 2012 6:54 pm
by Gez
ETTiNGRiNDER wrote:oddly, Linear and Cubic seemed to have reversed effects from what you had with Photoshop

They're not the same. Linear isn't bilinear; and cubic isn't bicubic, AFAIK.

Re: Downscaling resampling tutorial

PostPosted: Fri Feb 17, 2012 7:04 pm
by Cage
Another method of downscaling is to scale your texture x4 of your destination size ((x2, x3, work too) and use a Pixelate -> Mosaic filter or equivalent - it changes your picture into pixels.

Image

Then scale it to desired size with NEAREST/no resampling/pixel resize/whatever

This nets the same results as bilinear in PhotoShop, though.

Re: Downscaling resampling tutorial

PostPosted: Sat Feb 18, 2012 2:56 am
by printz
I like all downscaling variants, they make the texture look different enough depending on application.

Re: Downscaling resampling tutorial

PostPosted: Sat Feb 18, 2012 4:56 am
by NeuralStunner
I have something to add!

3x3 tile your texture before you scale it down, then crop the center back to intended final size. This makes sure that any blending will be tilable, and avoid sharp edges at the texture boundaries.