Image2Ansi in Unity

I've written an Image2Ansi converter app in UWP/C# for making terminal mode text art from images for command-line programs (think Node, Python, etc etc), but it's of course slow it's doing a pixel by pixel comparison with software WriteableBitmaps in UWP. So I thought maybe I might try rewriting it in Unity3D to see if I could get some performance gains, not to mention cross-platform compatibility.

Basically I have a big PNG that gives me a permutation of every foreground/background/ASCII character in CP437, and for every 9x16 block in my source image (after I've dithered it down to 16 colors by Jarvis-Judice-Ninke error diffusion) I compare it to each 9x16 font character, getting the sum of the euclidean distances of the colors of each block to get a score, whichever block has the lowest score is the winner for each iteration.

So I'm wondering what might be the best way to accomplish this in Unity. I tried loading an image from a Resource and then resizing it and loading it into a UI Raw Image, but it gives me a white sprite (code below). Should I be looking at some sort of shader to help accomplish this (I'm new to shaders and see a Compute Shader and Image Effect Shader but unsure which to choose)? Could be neat for a shader effect if it can be fast enough. End result needs to be able to persist back to the hard drive on the client (both as an ANSI and as a PNG of the result).



Image loading in error (in Start() method, inputTexture is a Texture2D in the Resources folder):

inputTexture = Resources.Load<Texture2D>("inputimage");

int width = inputTexture.width;
int height = inputTexture.height;
int newWidth = 720;
float scaleFactor = ((float)newWidth / (float)width);
int newHeight = (int)((float)height * scaleFactor);

newTexture = new Texture2D(width, height, TextureFormat.RGB24, false);
Graphics.CopyTexture(inputTexture, newTexture);
newTexture.Apply();
Debug.Log(newTexture.Resize(newWidth, newHeight, TextureFormat.RGB24, false));
newTexture.Apply();
UIImage.texture = newTexture;

The Debug.Log above gives true but sets the Raw Image to white, if I remove the resize it works. Any ideas?

 

I used TextureScaler to fix the scaling program. I'm on to Compute Shaders right now. Here's the problem I'm running into:

ComputeScript.cs:

Code (csharp):

1.  
2.     void Start () {
3.         inputImage = Resources.Load<Texture2D>("inputimage");
4.         int width = inputImage.width;
5.         int height = inputImage.height;
6.         int newWidth = 720;
7.         float scaleFactor = ((float)newWidth / (float)width);
8.         int newHeight = (int)((float)height * scaleFactor);
9.  
10.         Texture2D newTexture = new Texture2D(width, height, TextureFormat.RGB24, false);
11.         Color[] pixels = inputImage.GetPixels(0, 0, width, height);
12.         newTexture.SetPixels(0, 0, width, height, pixels);
13.         newTexture.Apply();
14.  
15.         TextureScaler.scale(newTexture, newWidth, newHeight, FilterMode.Point);
16.  
17.         inputFontTexture = Resources.Load<Texture2D>("vgafont");
18.         int fontWidth = inputFontTexture.width;
19.         int fontHeight = inputFontTexture.height;
20.  
21.         int kernel = compute.FindKernel("CSMain");
22.         result = new RenderTexture(fontWidth, fontHeight, 24);
23.         result.enableRandomWrite = true;
24.         result.Create();
25.  
26.         compute.SetTexture(kernel, "Result", result);
27.         compute.SetTexture(kernel, "ImageInput", newTexture);
28.         compute.SetTexture(kernel, "FontInput", inputFontTexture);
29.         compute.SetInt("InputCol", 20);
30.         compute.SetInt("InputRow", 10);
31.         compute.Dispatch(kernel, fontWidth / 8, fontHeight / 8, 1);
32.  
33.         int kernelProcess = compute.FindKernel("CSBestDistance");
34.        
35.         compute.SetTexture(kernelProcess, "Result", result);
36.  
37.         int bufferSize = 16 * 16 * 256;
38.         ComputeBuffer buffer = new ComputeBuffer(bufferSize, sizeof(float));
39.         compute.SetBuffer(kernelProcess, "ResultDistances", buffer);
40.         compute.Dispatch(kernelProcess, bufferSize / 16, 1, 1);
41.         float[] buffer2 = new float[bufferSize];
42.         buffer.GetData(buffer2);
43.         Debug.Log(buffer2.Min());
44.         //for (int z = 0; z < bufferSize; z++)
45.             //Debug.Log(buffer2[z]);
46.         buffer.Dispose();
47.     }
48.  

Compute Shader:

Code (csharp):

1.  
2. #pragma kernel CSMain
3. #pragma kernel CSBestDistance
4.  
5. RWTexture2D<float4> Result;
6. Texture2D<float4> ImageInput;
7. Texture2D<float4> FontInput;
8. int InputCol;
9. int InputRow;
10. RWTexture2D<float4> ResultDistances;
11. //RWStructuredBuffer<float2> ResultDistances;
12.  
13. [numthreads(8,8,1)]
14. void CSMain (uint3 id : SV_DispatchThreadID)
15. {
16.     int xoffset = InputCol * 9;
17.     int yoffset = InputRow * 16;
18.     //int inputoffset = yoffset + xoffset;
19.     int fontx = id.x % 9;
20.     int fonty = id.y % 16;
21.     float2 inputoffset = float2(xoffset + fontx, yoffset + fonty);
22.  
23.     float4 fontinput = FontInput[id.xy];
24.     float4 imageinput = ImageInput[inputoffset];
25.     float distanceInput = distance(fontinput, imageinput);
26.     Result[id.xy] = float4(distanceInput, distanceInput, distanceInput, 1);
27. }
28.  
29. [numthreads(16,1,1)]
30. void CSBestDistance (uint3 id: SV_DispatchThreadID) {
31.     int x = id.x % 2304;
32.     int y = (id.x - x) / 2304;
33.     ResultDistances[id.x] = Result[float2(x,y)].x;
34. }
35.  

When CSBestDistance comes back, I have values of all 1, but if I just do something like this:

ResultDistances[id.x] = id.x;

My buffer is filled as expected with values 0..65535. So I think it has to do something with the texture, when I look at the texture visually in the Editor after the CSMain kernel runs it gets Result as a texture just fine, it's a grayscale image showing the distances between the source and destination as a 2304x4096 RenderTexture. If I don't run compute.SetTexture(kernelProcess, "Result", result); when I run the second kernel I'll get back all 0's, if I do run it I get all 1's.

How do I get my renderTexture to pass appropriately so that I can chain kernels? Or is there a better way? Really my end result is, I just need a 2 element float array giving me the x/y of the lowest distance (which would be a third kernel to write to get the minimum of the distances in terms of x/y), and should be done on the GPU. Can I tell a single computer shader thread operation to kick off subroutines with multiple threads? I'm finding hard to get good documentation around compute shaders on these sorts of topics.