From bug-octave-request at bevo dot che dot wisc dot edu  Fri Dec 15 11:55:08 2000
Subject: saveimage writes wrong b/w images in some cases
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Kai Habel <kahacjde at calvados dot zrz dot TU-Berlin dot DE>
Cc: bug-octave <bug-octave at bevo dot che dot wisc dot edu>
Date: Fri, 15 Dec 2000 11:54:50 -0600

On  7-Aug-2000, Kai Habel <kahacjde at calvados dot zrz dot TU-Berlin dot DE> wrote:

| Bug report for Octave 2.1.31 configured for %OCTAVE_CANONICAL_HOST_TYPE%
| 
| Description:
| -----------
| 
|   saveimage writes distorted b/w images in same cases
| 
| Repeat-By:
| ---------
| 
|   X = [ones(42,22),zeros(42,22)];
|   imshow(X,2);
| 
| Fix:
| ---
| 
|   See patch appended. I have decided to rewrite the black/ white image
| section (ppb) for the ppm case. 
| 
| ChangeLog:
| 
| 2000-08-08  Kai Habel  <kai dot habel at gmx dot de>
| 
| 	* saveimage.m: fix distortion bug for ppm(pbm) image.

Sorry for the long delay.

I applied this patch.

Thanks!

jwe


*** /usr/local/share/octave/2.1.31/m/image/saveimage.m	Tue Jul 18 10:39:02 2000
| --- ./saveimage.m	Mon Aug  7 20:54:23 2000
| ***************
| *** 160,166 ****
|       tagline = sprintf ("# Created by Octave %s, %s",
|   		       __OCTAVE_VERSION__, time_string);
|   
| !     if (grey && map_nr == 2 && bw)
|   
|         if (map(1) != 0)
|           map = [0; 1];
| --- 160,166 ----
|       tagline = sprintf ("# Created by Octave %s, %s",
|   		       __OCTAVE_VERSION__, time_string);
|   
| !     if (grey && bw)
|   
|         if (map(1) != 0)
|           map = [0; 1];
| ***************
| *** 168,193 ****
|           map = [1; 0];
|         endif
|   
| !       n_long = rem (img_nc, 8);
| !       tmp = zeros (ceil (img_nc/8), img_nr);
|   
| !       for i = 1:img_nr
| !         idx = (i-1)*img_nc+1:i*img_nc;
| !         if (n_long > 0)
| !           img_row = [map(img(idx)); (zeros (8-n_long, 1))];
| !         else
| !           img_row = map(img(idx));
| !         endif
| ! 	l_img_row = length (img_row);
| !         if (img_nc < 8)
| !           for j = 1:8
| !             tmp(:,i) = tmp(:,i) + img_row (j) * 2^(8-j);
| !           endfor
| !         else
| !           for j = 1:8
| !             tmp(:,i) = tmp(:,i) + img_row (j:8:l_img_row) * 2^(8-j);
| !           endfor
| !         endif
|         endfor
|   
|         fid = fopen (filename, "w");
| --- 168,183 ----
|           map = [1; 0];
|         endif
|   
| !       k = ceil (img_nr/8);
| !       tmp = zeros (k, img_nc);
|   
| !       ## append columns with zeros to original img, that mod(cols,8) = 0 !
| !       bwimg = postpad (reshape (map(img), img_nr, img_nc), k * 8, 0);
| ! 
| !       b = kron (pow2 (7:-1:0)', ones (1, img_nc));
| ! 
| !       for i = 1:k
| !         tmp(i,:) = sum (bwimg(8*(i-1)+1:8*i,:) .* b);
|         endfor
|   
|         fid = fopen (filename, "w");
| 
| 



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