B

Task/Bitmap-Read-an-image-through-a-pipe/0DESCRIPTION

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+This task is the ''opposite'' of the [[PPM conversion through a pipe]]. In this task, using a delegate tool (like '''cjpeg''', one of the netpbm package, or '''convert''' of the ImageMagick package) we read an image file and load it into the data storage type [[Basic bitmap storage|defined here]]. We can also use the code from [[Read ppm file]], so that we can use PPM format like a (natural) bridge between the foreign image format and our simple data storage.

Task/Bitmap-Read-an-image-through-a-pipe/1META.yaml

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+---
+category:
+- Input Output
+note: Raster graphics operations

Task/Bitmap-Read-an-image-through-a-pipe/AutoHotkey/bitmap-read-an-image-through-a-pipe.ahk

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+ppm := Run("cmd.exe /c convert lena50.jpg ppm:-")
+                       ; pipe in from imagemagick
+img := ppm_read("", ppm) ;
+x := img[4,4] ; get pixel(4,4)
+y := img[24,24] ; get pixel(24,24)
+msgbox % x.rgb() " " y.rgb()
+img.write("lena50copy.ppm")
+return
+
+ppm_read(filename, ppmo=0) ; only ppm6 files supported
+{
+if !ppmo  ; if image not already in memory, read from filename
+  fileread, ppmo, % filename
+
+  index := 1
+  pos := 1
+
+  loop, parse, ppmo, `n, `r
+  {
+    if (substr(A_LoopField, 1, 1) == "#")
+      continue
+loop,
+{
+ if !pos := regexmatch(ppmo, "\d+", pixel, pos)
+break
+    bitmap%A_Index% := pixel
+    if (index == 4)
+      Break
+    pos := regexmatch(ppmo, "\s", x, pos)
+    index ++
+}
+  }
+
+  type := bitmap1
+  width := bitmap2
+  height := bitmap3
+  maxcolor := bitmap4
+  bitmap := Bitmap(width, height, color(0,0,0))
+  index := 1
+  i := 1
+  j := 1
+ bits := pos
+loop % width * height
+  {
+      bitmap[i, j, "r"]  := numget(ppmo, 3 * A_Index + bits, "uchar")
+      bitmap[i, j, "g"]  := numget(ppmo, 3 * A_Index + bits + 1, "uchar")
+      bitmap[i, j, "b"]  := numget(ppmo, 3 * A_Index + bits + 2, "uchar")
+
+      if (j == width)
+{
+	j := 1
+	i += 1
+}
+      else
+	j++
+}
+ return bitmap
+  }
+#include bitmap_storage.ahk ; from http://rosettacode.org/wiki/Basic_bitmap_storage/AutoHotkey
+#include run.ahk ; http://www.autohotkey.com/forum/viewtopic.php?t=16823

Task/Bitmap-Read-an-image-through-a-pipe/C/bitmap-read-an-image-through-a-pipe-1.c

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+image read_image(const char *name);

Task/Bitmap-Read-an-image-through-a-pipe/C/bitmap-read-an-image-through-a-pipe-2.c

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+#include "imglib.h"
+
+#define MAXCMDBUF 100
+#define MAXFILENAMELEN 256
+#define MAXFULLCMDBUF (MAXCMDBUF + MAXFILENAMELEN)
+image read_image(const char *name)
+{
+      FILE *pipe;
+      char buf[MAXFULLCMDBUF];
+      image im;
+
+      FILE *test = fopen(name, "r");
+      if ( test == NULL ) {
+         fprintf(stderr, "cannot open file %s\n", name);
+         return NULL;
+      }
+      fclose(test);
+
+      snprintf(buf, MAXFULLCMDBUF, "convert \"%s\" ppm:-", name);
+      pipe = popen(buf, "r");
+      if ( pipe != NULL )
+      {
+           im = get_ppm(pipe);
+           pclose(pipe);
+           return im;
+      }
+      return NULL;
+}

Task/Bitmap-Read-an-image-through-a-pipe/Go/bitmap-read-an-image-through-a-pipe.go

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+package main
+
+// Files required to build supporting package raster are found in:
+// * Bitmap
+// * Read a PPM file
+// * Write a PPM file
+
+import (
+    "fmt"
+    "os/exec"
+    "raster"
+)
+
+func main() {
+    // (A file with this name is output by the Go solution to the task
+    // "Bitmap/PPM conversion through a pipe," but of course any handy
+    // jpeg should work.)
+    c := exec.Command("djpeg", "pipeout.jpg")
+    pipe, err := c.StdoutPipe()
+    if err != nil {
+        fmt.Println(err)
+        return
+    }
+    err = c.Start()
+    if err != nil {
+        fmt.Println(err)
+        return
+    }
+    b, err := raster.ReadPpmFrom(pipe)
+    if err != nil {
+        fmt.Println(err)
+        return
+    }
+    err = b.WritePpmFile("pipein.ppm")
+    if err != nil {
+        fmt.Println(err)
+    }
+}

Task/Bitmap-Read-an-image-through-a-pipe/PicoLisp/bitmap-read-an-image-through-a-pipe.l

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+(setq *Ppm (ppmRead '("convert" "img.jpg" "ppm:-")))

Task/Bitmap-Read-an-image-through-a-pipe/Ruby/bitmap-read-an-image-through-a-pipe.rb

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+class Pixmap
+  def self.read_ppm(ios)
+    format = ios.gets.chomp
+    width, height = ios.gets.chomp.split.map {|n| n.to_i }
+    max_colour = ios.gets.chomp
+
+    if (not PIXMAP_FORMATS.include?(format)) or
+        width < 1 or height < 1 or
+        max_colour != '255'
+    then
+      ios.close
+      raise StandardError, "file '#{filename}' does not start with the expected header"
+    end
+    ios.binmode if PIXMAP_BINARY_FORMATS.include?(format)
+
+    bitmap = self.new(width, height)
+    height.times do |y|
+      width.times do |x|
+        # read 3 bytes
+        red, green, blue = case format
+          when 'P3' then ios.gets.chomp.split
+          when 'P6' then ios.read(3).unpack('C3')
+        end
+        bitmap[x,y] = RGBColour.new(red, green, blue)
+      end
+    end
+    ios.close
+    bitmap
+  end
+
+  def self.open(filename)
+    read_ppm(File.open(filename, 'r'))
+  end
+
+  def self.open_from_jpeg(filename)
+    read_ppm(IO.popen("convert jpg:#{filename} ppm:-", 'r'))
+  end
+end
+
+bitmap = Pixmap.open_from_jpeg('file.jpg')

Task/Bitmap-Read-an-image-through-a-pipe/Tcl/bitmap-read-an-image-through-a-pipe.tcl

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+package require Tk
+
+proc magickalReadImage {bufferImage fileName} {
+    set f [open |[list convert [file normalize $fileName] ppm:-] "rb"]
+    try {
+        $bufferImage put [read $f] -format ppm
+    } finally {
+        close $f
+    }
+}