Fixed grayscale handling in main.c and tricorn.c

Now grayscale files use a color pallete and in general should be smaller.

Implementierung/main.c

@@ -191,13 +191,7 @@ int main(int argc, char** argv)
     }
 
     float complex complexA = (starting_point_real + starting_point_imaginary*I);
-    int bytesPerColour;
-    if (colored)
-    {
-        bytesPerColour = 3;
-    } else {
-        bytesPerColour = 1;
-    }
+    int bytesPerColour = colored ? 3 : 1;
     
     ssize_t absolute_height = height >= 0 ? height : height * - 1;
     unsigned char *tempArr = malloc(width*absolute_height*bytesPerColour);// allocate image array on the heap to support large images as the stack is usually only 8 MB big
@@ -239,6 +233,7 @@ void save_bmp(const char *filename, unsigned char *img, size_t width, ssize_t he
 
     size_t image_size = actual_height * row_width;
     size_t file_size = image_size + 54; // File size = Image Size + Headers
+    size_t header_offset = color ? 54 : 1078; // If colored then offset = 54 if not we add offset = 54 + 1024; 1024 Bytes for color pallete
 
 
     // File header - contains information about the file
@@ -246,7 +241,7 @@ void save_bmp(const char *filename, unsigned char *img, size_t width, ssize_t he
         'B', 'M',           // BM - identifies file as a .bmp file
         0, 0, 0, 0,         // 4 bytes for file size - will be set later
         0, 0, 0, 0,         // Reserved
-        54, 0, 0, 0         // 4 bytes that specify the offset where the image array begins
+        0, 0, 0, 0         // 4 bytes that specify the offset where the image array begins
     };
 
     // Serialize the size into 4 bytes - (unsigned char) takes only bottom 4 bytes 1 2 3 4
@@ -255,6 +250,9 @@ void save_bmp(const char *filename, unsigned char *img, size_t width, ssize_t he
     file_header[4] = (unsigned char)(file_size >> 16);
     file_header[5] = (unsigned char)(file_size >> 24);
 
+    file_header[10] = (unsigned char)(header_offset);
+    file_header[11] = (unsigned char)(header_offset >> 8);
+
     // Info header - contains information about the image itself
     unsigned char info_header[40] = { 
         40, 0, 0, 0,        // Size of this header    
@@ -294,6 +292,22 @@ void save_bmp(const char *filename, unsigned char *img, size_t width, ssize_t he
     fwrite(file_header,1,14,fptr); 
     fwrite(info_header,1,40,fptr);
 
+
+    //If image is grayscale write color dictionary to tell reader what color to visualise for each value
+    // Row 0 - Value 0: [R=0;B=0;G=0]
+    // ...
+    //Row i - Value i: [R=i;B=i;G=i]
+    if (!color) {
+        unsigned char palette[1024];
+        for (int i = 0; i < 256; i++) {
+            palette[i * 4 + 0] = i; // B
+            palette[i * 4 + 1] = i; // G
+            palette[i * 4 + 2] = i; // R
+            palette[i * 4 + 3] = 0; // Reserved (Padding)
+        }
+        fwrite(palette, 1, 1024, fptr);
+    }
+
     // Save padding bytes as array so we can write from it easily to the file later
     unsigned char padding_bytes[3] = {0, 0, 0};