The Texture2D equivalent of Alpha is Transparency for LoadImage png

Hi all,

With pngs imported into my Unity project, the standard 'Texture' type has a check box with 'Alpha Is Transparency'. If I check this, my texture has a nice transparent back ground, as opposed to black. All is lovely.

If I don't have the png imported though, and instead load it with Texture2D.LoadImage.

I only have the black background option.

Is there a way to make the loaded png behave the same as if it were imported.

Thanks

The images below show the main character with the Texture2D.LoadImage, vs the png imported in Unity with 'Alpha is Transparency' set. It's very minor differences, but i'm keen not to have the slight seam around the top of the leg, as well as the seam where the arm connects to the body, and the small seam at the top of the chin.

 

Hi Karl, thanks very much for your reply.

Sadly I don't think Edge Padding is something that will help. Unless i'm mistaken, pngs don't have an Alpha channel (just alpha transparency), so I can't dilate the image and then use the alpha channel. To show only the bits of the png I want?

Not sure if it will help but below is how my player is rendered on quads/triangles, along with the sprite sheet used.

 

Hi! Bumping this. I have way too many PNG files to do the Photoshop trick manually for each one (> 1000 files), and I'm in the editor, so I have access to any code I want.

Is there a way to apply the alpha dilation filter programmatically @karl_jones ?

 

No, because the texture isn't an asset, it never gets imported. It's created from an in-memory byte array via LoadImage.

 

I'm not sure if this is relevant, but I hope it is
I was having trouble importing PNG files with corrupted alpha channels, this is how I solved it:

Code (CSharp):

1. byte[] fileData = File.ReadAllBytes(filePath);
2.  
3. Texture2D tex = new Texture2D(2, 2, TextureFormat.RGBA32, false);
4. tex.LoadImage(fileData);
5.  
6. Texture2D texPNG = new Texture2D(tex.width, tex.height, TextureFormat.RGBA32, false);
7. texPNG.SetPixels(tex.GetPixels());
8. texPNG.Apply();

 

Well, thanks a lot! This worked for me. My usecase was: I wanted user to add a texture (amazon logo 'a' for isntance) through selecting the PNG file. The problem was, the logo was getting a cyan tint or sometimes red instead of black color if I set alpha channel traversing through all pixels.

Just tried this and it worked!

 

How did you apply it? Did you transformed it into a sprite and then assigned the sprite to the sprite renderer? thanks

 

Hi, sorry for bumping this, I'm trying to do something similar, taking a screenshot and saving it, and the screenshot I want to take is for a single character, in other words I need everything else to be transparent, here's the code:

Code (CSharp):

1. int width = Screen.width;
2. int height = Screen.height;
3. Texture2D screenshotTexture = new Texture2D(width,
4. height, TextureFormat.RGBA32, false);
5. Rect rect = new Rect(0, 0, width, height);
6. screenshotTexture.ReadPixels(rect, 0, 0);
7. screenshotTexture.Apply();
8.  
9. byte[] byteArray = screenshotTexture.EncodeToPNG();
10. System.IO.File.WriteAllBytes(_path, byteArray);

It does take screenshot but not with transparency even if the texture format is RGBA32, so I'm guessing it has something to do with Texture2D.alphaIsTransparency, since the result replaces alpha with black color, am I missing something?

Thanks,

 

Hi!
I found the following solution for the 'Alpha Is Transparency' option:

Code (CSharp):

1. public static void AlphaIsTransparency(this Texture2D texture)
2. {
3.     Color[] pixels = texture.GetPixels();
4.     for (int i = 0; i < pixels.Length; i++)
5.     {
6.         if(Mathf.Approximately(pixels[i].a, 0))
7.             pixels[i] = new Color();
8.     }
9.     texture.SetPixels(pixels);
10.     texture.Apply();
11. }

Usage:

Code (CSharp):

1. var texture = new Texture2D(
2.     512, 512,
3.     TextureFormat.RGBA32, false
4. );
5. texture.LoadImage(File.ReadAllBytes(fileFullName));
6. texture.AlphaIsTransparency();

In my case, it fixes filtering artifacts around transparent areas of externally imported PNG's like 'Alpha Is Transparency' does.