Init quantization and PPM, Fixes for bayer2rgb

Assignment_1/bayer2rgb.m

@@ -209,7 +209,7 @@ function xc = bayer2rgb(xb, M, N, method)
             
             for currentCol = 1:N
                 if ((mod(centerPointRow(currentRow), 2) == 0 && ...
-                        mod(centerPointCol(currentCol), 2)) == 0 || ...
+                        mod(centerPointCol(currentCol), 2) == 0) || ...
                         (mod(centerPointRow(currentRow), 2) ~= 0 && ...
                         mod(centerPointCol(currentCol), 2) ~= 0))
                     % This point of the original image DOES contain
@@ -248,11 +248,11 @@ function xc = bayer2rgb(xb, M, N, method)
                         fixedCenterPointCol = centerPointCol(currentCol) + 1;
                     end
                     
-                    if (fixedCenterPointRow < 1)
-                        % Fix for the marginal first row case
-                        fixedCenterPointRow = 1;
-                        fixedCenterPointCol = fixedCenterPointCol - 1;
-                    end
+%                     if (fixedCenterPointRow < 1)
+%                         % Fix for the marginal first row case
+%                         fixedCenterPointRow = 1;
+%                         fixedCenterPointCol = fixedCenterPointCol - 1;
+%                     end
                     
                     xc.green(currentRow, currentCol) = ...
                         tiltedInterp(gridPointsCoordinatesX(currentCol), ...
@@ -277,6 +277,29 @@ end
 
 
 function value = tiltedInterp(xw, yw, xc, yc, xbPadded)
+    % Rotates the nearest points by 45 degrees
+    x1 = (xc - 1) * cosd(45) - yc * sind(45);
+    y1 = (xc - 1) * sind(45) + yc * cosd(45);
+    
+    x2 = (xc + 1) * cosd(45) - yc * sind(45);
+    y2 = xc * sind(45) + (yc + 1) * cosd(45);
+    
+    lowerLeftInterpPoint = ...
+        ((x2 - xw) / (x2 - x1)) * ...
+        xbPadded(yc + 2, xc - 1 + 2) + ...
+        ((xw - x1) / (x2 - x1)) * ...
+        xbPadded(yc + 1 + 2, xc + 2);
+
+    upperRightInterpPoint = ...
+        ((x2 - xw) / (x2 - x1)) * ...
+        xbPadded(yc - 1 + 2, xc + 2) + ...
+        ((xw - x1) / (x2 - x1)) * ...
+        xbPadded(yc + 2, xc + 1 + 2);
+
+    value2 = ...
+        (y2 - yw) / (y2 - y1) * lowerLeftInterpPoint + ...
+        (yw - y1) / (y2 - y1) * upperRightInterpPoint;
+    
     % Calculates the vertical displacement of the main diagonal that
     % crosses this point
     bw = yw - xw;
@@ -289,9 +312,9 @@ function value = tiltedInterp(xw, yw, xc, yc, xbPadded)
     % the lower point and the left point
     dist = sqrt((x1 - xw) ^ 2 + (x1 + bw - yw) ^ 2);
     
-    % Calculates the lengths of the upper parts of the lines connecting the
+    % Calculates the length of the upper part of the line connecting the
     % points
-    h1 = sqrt(((xc - 1 - xw) ^ 2 + (yc - yw) ^ 2) - dist ^ 2);
+    h1 = abs(sqrt(((xc - 1 - xw) ^ 2 + (yc - yw) ^ 2) - dist ^ 2));
     
     lowerLeftInterpPoint = ...
         ((sqrt(2) - h1) / sqrt(2)) * ...
@@ -308,18 +331,12 @@ function value = tiltedInterp(xw, yw, xc, yc, xbPadded)
     value = ...
         (sqrt(2) - dist) / sqrt(2) * lowerLeftInterpPoint + ...
         dist / sqrt(2) * upperRightInterpPoint;
+    
+    value = (xbPadded(yc + 2, xc - 1 + 2) + ...
+        xbPadded(yc + 2, xc + 1 + 2) + ...
+        xbPadded(yc - 1 + 2, xc + 2) + ...
+        xbPadded(yc + 1 + 2, xc + 2)) / 4;
+%     if (value ~= value2)
+%         disp(1);
+%     end
 end
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Assignment_1/imagedequant.m

@@ -0,0 +1,18 @@
+function x = imagedequant(q, w1, w2, w3)
+%imagedequant dequantizes the pixel values of a tri-chromatic image
+%   Usage x = imagedequant(q, w1, w2, w3), where:
+%       Inputs
+%       - q is the input image who's values are going to be dequantized
+%       - w1 is the quantization step size for the first channel (red)
+%       - w2 is the quantization step size for the second channel (green)
+%       - w3 is the quantization step size for the third channel (blue)
+%
+%       Output
+%       - x is the image with the dequantized values
+
+    x = struct;
+    x.red = mydequant(q.red, w1);
+    x.green = mydequant(q.green, w2);
+    x.blue = mydequant(q.blue, w3);
+end
+

Assignment_1/imagequant.m

@@ -0,0 +1,17 @@
+function q = imagequant(x, w1, w2, w3)
+%imagequant quantizes the pixel values of a tri-chromatic image
+%   Usage q = imagequant(x, w1, w2, w3), where:
+%       Inputs
+%       - x is the input image who's values are going to be quantized
+%       - w1 is the quantization step size for the first channel (red)
+%       - w2 is the quantization step size for the second channel (green)
+%       - w3 is the quantization step size for the third channel (blue)
+%
+%       Output
+%       - q is the image with the quantized values
+
+    q = struct;
+    q.red = myquant(x.red, w1);
+    q.green = myquant(x.green, w2);
+    q.blue = myquant(x.blue, w3);
+end

Assignment_1/mydequant.m

@@ -0,0 +1,14 @@
+function x = mydequant(q, w)
+%Implementation of a uniform, symmetric dequantizer without a dead zone
+%   Usage x = mydequant(q, w), where:
+%       Inputs
+%       - q is the input that is going to be dequantized, this can be a
+%       scalar, a column or row vector or a matrix
+%       - w is the quantization step size
+%
+%       Output
+%       - x holds the quantized value(s), depending on the input this may
+%       be a scalar, a column or row vector or a matrix
+
+    x = (2 * q .* w + w) / 2;
+end

Assignment_1/myquant.m

@@ -0,0 +1,14 @@
+function q = myquant(x, w)
+%Implementation of a uniform, symmetric quantizer without a dead zone
+%   Usage q = myquant(x, w), where:
+%       Inputs
+%       - x is the input that is going to be quantized, this can be a
+%       scalar, a column or row vector or a matrix
+%       - w is the quantization step size
+%
+%       Output
+%       - q holds the quantized value(s), depending on the input this may
+%       be a scalar, a column or row vector or a matrix
+
+    q = floor(x ./ w);
+end

Assignment_1/saveasppm.m

@@ -0,0 +1,47 @@
+function saveasppm(x, filename, K)
+%saveasppm encodes an image as PPM and saves it to the disk
+%   Usage saveasppm(x, filename, K), where:
+%       Inputs
+%       - x is the input image
+%       - filename is the path and filename of the file where the resulting
+%           PPM image is going to be saved
+%       - K is the maximum value of brightness
+
+    file = fopen(filename, 'wt+');
+    
+    fwrite(file, 'P6');
+    fwrite(file, ' ');
+    fwrite(file, int2str(size(x.red, 1)));
+    fwrite(file, ' ');
+    fwrite(file, int2str(size(x.red, 2)));
+    fwrite(file, ' ');
+    fwrite(file, int2str(K));
+    fwrite(file, newline);
+    
+    if K < 256
+        precision = 'integer*1';
+        precisionBytes = 1;
+        machinefmt = 'l';
+    else
+        precision = 'integer*2';
+        precisionBytes = 2;
+        machinefmt = 'b';
+    end
+    
+    for row = 1:size(x.red, 1)
+        for column = 1:size(x.red, 2)
+            fwrite(file, x.red(row, column), precision, machinefmt);
+            fwrite(file, ' ');
+            fwrite(file, x.green(row, column), precision, machinefmt);
+            fwrite(file, ' ');
+            fwrite(file, x.blue(row, column), precision, machinefmt);
+            fwrite(file, ' ');
+        end
+    end
+
+%     combined = B(:,[1;1]*(1:size(B,2)));
+%     combined(:,1:2:end) = A;
+
+    fclose(file);
+end
+