Bitmap/Read an image through a pipe

Bitmap/Read an image through a pipe
You are encouraged to solve this task according to the task description, using any language you may know.

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 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.

AutoHotkey

Works with: AutoHotkey_L

Uses StdoutTovar.ahk <lang AutoHotkey>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  
 }

1. include bitmap_storage.ahk ; from http://rosettacode.org/wiki/Basic_bitmap_storage/AutoHotkey
2. include run.ahk ; http://www.autohotkey.com/forum/viewtopic.php?t=16823

</lang>

C

Works with: POSIX version .1-2001

Here I've used convert by ImageMagick. It is up to the program to understand the source file type; in this way, we can read theoretically any image format ImageMagick can handle. The get_ppm function defined in Read ppm file is used.

<lang c>image read_image(const char *name);</lang>

<lang c>#include "imglib.h"

1. define MAXCMDBUF 100
2. define MAXFILENAMELEN 256
3. 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;

}</lang>

Go

This example uses convert to convert the test image for the flood fill task. It reads through the pipe as required for this task, then writes as a .ppm file convenient for the flood fill task. <lang go>package main

// Files required to build supporting package raster are found in: // * Bitmap // * Read a PPM file // * Write a PPM file

import (

   "log"
   "os/exec"
   "raster"

)

func main() {

   c := exec.Command("convert", "Unfilledcirc.png", "-depth", "1", "ppm:-")
   pipe, err := c.StdoutPipe()
   if err != nil {
       log.Fatal(err)
   }
   if err = c.Start(); err != nil {
       log.Fatal(err)
   }
   b, err := raster.ReadPpmFrom(pipe)
   if err != nil {
       log.Fatal(err)
   }
   if err = b.WritePpmFile("Unfilledcirc.ppm"); err != nil {
       log.Fatal(err)
   }

}</lang>

Mathematica

This example is untested. Please check that it's correct, debug it as necessary, and remove this message.

<lang Mathematica>Export["out.bmp", ImportString[InputString[], "PPM"]];</lang>

OCaml

The read_ppm function of the page read ppm file and used by the code below would need to be changed to take as parameter an input channel instead of the filename. <lang ocaml>let read_image ~filename =

 if not(Sys.file_exists filename)
 then failwith(Printf.sprintf "the file %s does not exist" filename);
 let cmd = Printf.sprintf "convert \"%s\" ppm:-" filename in
 let ic, oc = Unix.open_process cmd in
 let img = read_ppm ~ic in
 (img)

</lang>

Perl 6

Works with: Rakudo version 2017.09

Uses pieces from Bitmap and Read a PPM file tasks. Included here to make a complete, runnable program.

Uses imagemagick convert to pipe the image in.

<lang perl6>class Pixel { has UInt ($.R, $.G, $.B) } class Bitmap {

   has UInt ($.width, $.height);
   has Pixel @.data;

}

role PPM {

   method P6 returns Blob {

"P6\n{self.width} {self.height}\n255\n".encode('ascii') ~ Blob.new: flat map { .R, .G, .B }, self.data

   }

}

sub getline ( $proc ) {

   my $line = '#'; # skip comment when reading a .png
   $line = $proc.out.get while $line.substr(0,1) eq '#';
   $line;

}

my $filename = './camelia.png';

my $proc = run 'convert', $filename, 'ppm:-', :enc('ISO-8859-1'), :out;

my $type = getline($proc); my ($width, $height) = getline($proc).split: ' '; my $depth = getline($proc);

my Bitmap $b = Bitmap.new( width => $width.Int, height => $height.Int) but PPM;

$b.data = $proc.out.slurp.ords.rotor(3).map:

 { Pixel.new(R => .[0], G => .[1], B => .[2]) };

'./camelia.ppm'.IO.open(:bin, :w).write: $b.P6;</lang>

See camelia image here.

PicoLisp

<lang PicoLisp>(setq *Ppm (ppmRead '("convert" "img.jpg" "ppm:-")))</lang>

Racket

<lang racket>

(define (read-ppm port)

 (parameterize ([current-input-port port])
   (define magic (read-line))
   (match-define (list w h) (string-split (read-line) " "))
   (define width (string->number w))
   (define height (string->number h))
   (define maxcol (string->number (read-line)))
   (define bm (make-object bitmap% width height))
   (define dc (new bitmap-dc% [bitmap bm]))
   (send dc set-smoothing 'unsmoothed)
   (define (adjust v) (* 255 (/ v maxcol)))
   (for/list ([x width])
     (for/list ([y height])
       (define red (read-byte))
       (define green (read-byte))
       (define blue (read-byte))
       (define color (make-object color% (adjust red) (adjust green) (adjust blue)))
       (send dc set-pen color 1 'solid)
       (send dc draw-point x y)))
   bm))

(define (image->bmp filename)

 (define command (format "convert ~a ppm:-" filename))
 (match-define (list in out pid err ctrl)  (process command))
 (define bmp (read-ppm in))
 (close-input-port in)
 (close-output-port out)
 bmp)

(image->bmp "input.jpg")</lang>

Ruby

Extending Read ppm file#Ruby and PPM conversion through a pipe#Ruby. Uses the ImageMagick convert tool.

<lang ruby>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')</lang>

Tcl

Works with: Tcl version 8.6

Library: Tk

<lang tcl>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
   }

}</lang>

zkl

Translation of: C

Uses the PPM class from http://rosettacode.org/wiki/Bitmap/Bresenham%27s_line_algorithm#zkl

Using the convert utility by ImageMagick: <lang zkl>p:=System.popen(0'|convert "fractalTree.jpg" ppm:-|,"r"); img:=PPM.readPPM(p); p.close();</lang>