langs a-z

Task/Bitmap-Histogram/OCaml/bitmap-histogram-1.ocaml

@@ -0,0 +1,14 @@
+type histogram = int array
+
+let get_histogram ~img:gray_channel =
+  let width = Bigarray.Array2.dim1 gray_channel
+  and height = Bigarray.Array2.dim2 gray_channel in
+  let t = Array.make 256 0 in
+  for x = 0 to pred width do
+    for y = 0 to pred height do
+      let v = gray_get_pixel_unsafe gray_channel x y in
+      t.(v) <- t.(v) + 1;
+    done;
+  done;
+  (t: histogram)
+;;

Task/Bitmap-Histogram/OCaml/bitmap-histogram-2.ocaml

@@ -0,0 +1,15 @@
+let histogram_median (h : histogram) =
+
+  let from = 0 and to_ = 255 in
+  let left = h.(from) and right = h.(to_) in
+
+  let rec aux from to_ left right =
+    if from = to_
+    then (from)
+    else
+      if left < right
+      then aux (succ from) to_ (left + h.(from)) right
+      else aux from (pred to_) left (right + h.(to_))
+  in
+  aux from to_ left right
+;;

Task/Bitmap-Histogram/OCaml/bitmap-histogram-3.ocaml

@@ -0,0 +1,24 @@
+let () =
+  let img = read_ppm ~filename:"/tmp/foo.ppm" in
+
+  let width, height = get_dims img in
+  let res = new_img ~width ~height in
+
+  let g_img = to_grayscale ~img in
+  let h = get_histogram g_img in
+  let m = histogram_median h in
+
+  let light = (255, 255, 0)
+  and dark = (127, 0, 127) in
+
+  for x = 0 to pred width do
+    for y = 0 to pred height do
+      let v = gray_get_pixel_unsafe g_img x y in
+      if v > m
+      then put_pixel_unsafe res light x y
+      else put_pixel_unsafe res dark x y
+    done;
+  done;
+
+  output_ppm ~oc:stdout ~img:res;
+;;

Task/Bitmap-Histogram/Octave/bitmap-histogram.octave

@@ -0,0 +1,52 @@
+function h = imagehistogram(imago)
+  if ( isgray(imago) )
+    for j = 0:255
+      h(j+1) = numel(imago( imago == j ));
+    endfor
+  else
+    error("histogram on gray img only");
+  endif
+endfunction
+
+% test
+im = jpgread("Lenna100.jpg");
+img = rgb2gray(im);
+h = imagehistogram(img);
+% let's try to show the histogram
+bar(h);
+pause;
+
+% in order to obtain the requested filtering, we
+% can use median directly on the img, and then
+% use that value, this way:
+m = median(reshape(img, 1, numel(img)));
+disp(m);
+ibw = img;
+ibw( img > m ) = 255;
+ibw( img <= m ) = 0;
+jpgwrite("lennamed_.jpg", ibw, 100);
+% which disagree (128) with the m computed with histog_med (130).
+% If we compute it this way:
+% m = sort(reshape(img, 1, numel(img)))(ceil(numel(img)/2));
+% we obtain 130... but builtin median works as expected, since
+% N (number of pixel of Lenna) is even, not odd.
+
+% but let's use our histogram h instead
+function m = histog_med(histog)
+  from = 0; to = 255;
+  left = histog(from + 1); right = histog(to+1);
+  while ( from != to )
+    if ( left < right )
+      from++; left += histog(from+1);
+    else
+      to--; right += histog(to+1);
+    endif
+  endwhile
+  m = from;
+endfunction
+
+m = histog_med(h);
+disp(m);
+ibw( img > m ) = 255;
+ibw( img <= m ) = 0;
+jpgwrite("lennamed.jpg", ibw, 100);

Task/Bitmap-Histogram/PureBasic/bitmap-histogram.purebasic

@@ -0,0 +1,63 @@
+Procedure getHistogram(image, Array histogram(1))
+  Protected w = ImageWidth(image) - 1
+  Protected h = ImageHeight(image) - 1
+  Dim histogram(255) ;output
+
+  StartDrawing(ImageOutput(image))
+    For x = 0 To w
+      For y = 0 To h
+        lum = Red(Point(x, y)) ;the Green or Blue color components could be used also
+        histogram(lum) + 1
+      Next
+    Next
+  StopDrawing()
+EndProcedure
+
+Procedure median(Array histogram(1))
+  Protected low, high = 255, left, right
+
+  While low <> high
+    If left < right
+      low + 1
+      left + histogram(low)
+    Else
+      high - 1
+      right + histogram(high)
+    EndIf
+  Wend
+  ProcedureReturn low
+EndProcedure
+
+Procedure blackAndWhite(image, median)
+  Protected w = ImageWidth(image) - 1
+  Protected h = ImageHeight(image) - 1
+  CallDebugger
+  StartDrawing(ImageOutput(image))
+    For x = 0 To w
+      For y = 0 To h
+        If Red(Point(x, y)) < median ;the Green or Blue color components could be used also
+          Plot(x, y, $000000) ;black
+        Else
+          Plot(x, y, $FFFFFF) ;white
+        EndIf
+      Next
+    Next
+  StopDrawing()
+EndProcedure
+
+Define sourceFile.s, outputFile.s, image = 3, m
+Dim histogram(255)
+
+sourceFile = OpenFileRequester("Select source image file", "*.ppm", "PPM image (*.ppm)|PPM", 0)
+
+If sourceFile And LCase(GetExtensionPart(sourceFile)) = "ppm"
+  LoadImagePPM(image, sourceFile)
+  ImageGrayout(image)
+
+  getHistogram(image,histogram())
+  m = median(histogram())
+  blackAndWhite(image, m)
+
+  outputFile = Left(sourceFile, Len(sourceFile) - Len(GetExtensionPart(sourceFile))) + "_bw." + GetExtensionPart(sourceFile)
+  SaveImageAsPPM(image, outputFile, 1)
+EndIf

Task/Bitmap-Histogram/Vedit-macro-language/bitmap-histogram.vedit

@@ -0,0 +1,10 @@
+:HISTOGRAM:
+#30 = Buf_Free			     // #30 = buffer to store histogram data
+for (#9=0; #9<256; #9++) {
+    Out_Reg(21) TC(#9) Out_Reg(Clear)		// @21 = intensity value to be counted
+    Buf_Switch(#15)				// switch to image buffer
+    #8 = Search(@21, CASE+BEGIN+ALL+NOERR)	// count intensity values
+    Buf_Switch(#30)				// switch to histogram buffer
+    Num_Ins(#8, FILL)				// store count
+}
+Return