Initial commit

image_proc.c

@@ -0,0 +1,99 @@
+#include "image_proc.h"
+#include <stdlib.h>
+#include <string.h>
+#include <windows.h>
+
+int ExtractGray(const uint8_t *srcPixels, int w, int h, int bpp, GrayImage *outImg){
+    if(!srcPixels || w<=0 || h<=0) return 0;
+    int srcBytesPerPixel = bpp / 8;
+    int srcStride = ((w * srcBytesPerPixel + 3) / 4) * 4;
+    outImg->width = w;
+    outImg->height = h;
+    outImg->stride = w;
+    size_t total = (size_t)w * h;
+    outImg->data = (uint8_t*)malloc(total);
+    if(!outImg->data) return 0;
+    outImg->rows = (uint8_t**)malloc(sizeof(uint8_t*) * h);
+    if(!outImg->rows){
+        free(outImg->data);
+        outImg->data = NULL;
+        return 0;
+    }
+    for(int y=0; y<h; ++y){
+        outImg->rows[y] = outImg->data + (size_t)y * w;
+    }
+
+    for(int y=0; y<h; ++y){
+        const uint8_t *srcLine = srcPixels + (size_t)(h - 1 - y) * srcStride;
+        uint8_t *dstLine = outImg->rows[y];
+        if(bpp == 8){
+            memcpy(dstLine, srcLine, (size_t)w);
+        } else if(bpp == 24 || bpp == 32){
+            for(int x=0; x<w; ++x){
+                const uint8_t *p = srcLine + x * srcBytesPerPixel;
+                uint8_t B = p[0], G = p[1], R = p[2];
+                uint8_t Y = (uint8_t)((R*77 + G*150 + B*29) >> 8);
+                dstLine[x] = Y;
+            }
+        } else {
+            free(outImg->rows); free(outImg->data);
+            memset(outImg,0,sizeof(*outImg));
+            return 0;
+        }
+    }
+    return 1;
+}
+
+void FreeGray(GrayImage *img){
+    if(!img) return;
+    free(img->rows);
+    free(img->data);
+    memset(img,0,sizeof(*img));
+}
+
+int Build8BitDIB(const GrayImage *img, BITMAPINFO **outBMI, uint8_t **outPixels){
+    if(!img || !img->data) return 0;
+    int w = img->width;
+    int h = img->height;
+    int bpp = 8;
+    int dstStride = ((w * (bpp/8) + 3)/4)*4;
+    size_t pixelBytes = (size_t)dstStride * h;
+
+    size_t bmiSize = sizeof(BITMAPINFOHEADER) + 256 * sizeof(RGBQUAD);
+    BITMAPINFO *bmi = (BITMAPINFO*)calloc(1, bmiSize);
+    if(!bmi) return 0;
+
+    bmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
+    bmi->bmiHeader.biWidth = w;
+    bmi->bmiHeader.biHeight = h;         
+    bmi->bmiHeader.biPlanes = 1;
+    bmi->bmiHeader.biBitCount = 8;
+    bmi->bmiHeader.biCompression = BI_RGB;
+    bmi->bmiHeader.biSizeImage = (DWORD)pixelBytes;
+    bmi->bmiHeader.biClrUsed = 256;
+
+    for(int i=0;i<256;i++){
+        bmi->bmiColors[i].rgbBlue  = (BYTE)i;
+        bmi->bmiColors[i].rgbGreen = (BYTE)i;
+        bmi->bmiColors[i].rgbRed   = (BYTE)i;
+        bmi->bmiColors[i].rgbReserved = 0;
+    }
+
+    uint8_t *pixels = (uint8_t*)malloc(pixelBytes);
+    if(!pixels){
+        free(bmi);
+        return 0;
+    }
+    for(int y=0; y<h; ++y){
+        uint8_t *dstLine = pixels + (size_t)(h - 1 - y) * dstStride;
+        const uint8_t *srcLine = img->rows[y];
+        memcpy(dstLine, srcLine, (size_t)w);
+        if(dstStride > w){
+            memset(dstLine + w, 0, dstStride - w);
+        }
+    }
+
+    *outBMI = bmi;
+    *outPixels = pixels;
+    return 1;
+}