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[Tutorial] How to resize Textures.

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enVy's picture
enVy
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First of all i want to state out that YOU CAN use 128px/512px patches along with a 64/32px Texturepack. So you're NOT forced to use the same resolution as the Texturepack has.
Because of the overall theme of Sphax the visual difference between 128px & 64px isn't that big.

If you are worried about your performance, then you can resize your textures quite easily without loosing that much quality. I only explain how it works in photoshop, since it's my weapon of choice but it should work also with Gimp or Paint.NET.

The reason why i'm posting this is, i've seen in quite a lot posts that people ask for a 64px version of a patch which is ok but since it's so simple you can make it yourself. This way Patch creators can focus on new added blocks/items and you can almost instantly get your 64px version. Anyway enough preload, let's get started...

1. First of load your texture/sheet into PS, by either drag&drop it from the zip or by opening the image.

2. This step isn't required if you're not planing to change something.
For better alignment you should setup your grid. To do so go to "Edit - Preferences - Guides, Grid & Slices" and change the " Gridline Every" to 64 & pixels or if you work on a 128px Texturesheet to 128 & pixels. The subdivision count should be set to 2, this is particular useful when working on item sheets.
IMAGE(http://i.imgur.com/Oidal35.jpg)

3. Ok now for the resize.
There are two ways to resize, one for upscale and one for downscale.
You may ask yourself why shouldn't i just hit that damn Resize button? Well the answer is simple, because of the Interpolation. I'm not going into the calculation process since it would go beyond the constraints, but in short using the wrong method would end up either in a highly blurry or to crisp texture.

Ok let's say you want to scale down your texture from 128px to 64px. All you have to do is go to "Image - Image Size" inside the upcoming window you need to change the Width and Height from 2048 pixels to 1024 pixels. You can check all 3 checkboxes, Scale Styles would make sure that added effects will be scale properly, Constrain Proportions will keep the Aspect Ratio and Resample Image will make sure that you can Resize the Image.

Now to the important part! You see a Dropdown list with 5 to 6 options (depending on the version of PS you have).
IMAGE(http://i.imgur.com/7AU22KM.jpg)

- Nearest Neighbor (preserve hard edges). Is probably the best option for scaling up textures in Minecraft, since it makes sure that their is "no" bluring going on. But can produce jagged edges.

- Bilinear. As stated out by HanFox in Post #3 is the proper option to downscale your images although that it removes some contrast from your texture.
IMAGE(http://i.imgur.com/k7p04dV.gif)

- Bicubic (best for smooth gradients). Isn't that useful for us, since it destroys most hard edges by blending them slightly together.
IMAGE(http://i.imgur.com/N1qLRIl.gif)

- Bicubic Smoother (best for enlargement). No matter that you might think, "well it's for enlargement i should use it" i have to deny it. This is mainly used for really large images since it takes care of edge smoothing. If you would upscale your textures with it, they would become blurry!

- Bicubic Sharper (best for reduction). This option could be used to downsize your images but it still creates blurry edges. You can imagine this function like a first pass blur and a 2nd pass sharpening. The effect is really subtle but it seems to keep some contrast on the edges.
IMAGE(http://i.imgur.com/mLHu9bD.gif)

All in all the best option for Down-scaling your texture is indeed Bilinear (thanks HanFox for pointing me in the right direction) since it keeps most of the details we need.

If you really want to go even further into the process you can use High-Pass Sharpening to regain some of the details that you lost in the process. If used correct it will increase the quality a lot.
IMAGE(http://i.imgur.com/McMvvVc.gif)

A layered Demo of all Resize options.
So you can zoom in and out to see the differences a bit better.
http://goo.gl/qxYr6 (Google Drive)

Thanks again HanFox for sharing your insight!
Any further questions or critics are more than welcome, i'll try to help as best as i can.

All the best Happy
-enVy

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TrAnE's picture
TrAnE
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I released a major BDcraft patchI searched for an answer myselfThe Cake is a lieI explored bdcraft websiteI like to comment everythingI love to post here
Joined: 30/08/2012

Good tutorial. Happy
P.s.: What the patch in the screenshots?

enVy's picture
enVy
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Thanks! The Patch in the back is from Steve Carts 2 by HanFox.

I'm currently working on a patch for Applied Energistics since i really dig the Mod. Besides that i'm trying to find a way to speed up the general process by playing around with Photoshop Actions. I still have to do some research on how to create textures that fit well in the Sphax theme but as soon as i got something useful up i will share it with all of you.

Best regards Happy

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Nearest Neighbour is probably the worst you can use for downscaling. You lose all the smooth edges and end up with a jagged mess. It's the best for upscaling vanilla 16x to whatever else as you keep the pixel art though.

Sphax uses Bilinear to downscale. It's not a "mix" between NN and Bicubic either, it's a "triangle". It takes the average of the points in that triangle to come up with the best look.

NN basically just takes a point and uses that and Bicubic takes a square and averages it out which is why you get hard corners with that, too.

ImageMagick's manual goes in to things in great detail:
http://www.imagemagick.org/Usage/filter/

enVy's picture
enVy
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Thanks for pointing me in the right direction, this was pretty useful! Happy
You're absolutely right about NN i've corrected my post and made everything a bit more detailed.
But i think this should be enough for now, since it's more aimed at people who are too impatient to wait for a proper 64px version.