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1 ## Copyright (C) 1996, 1997 John W. Eaton |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 2, or (at your option) |
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8 ## any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, write to the Free |
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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18 ## 02110-1301, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} imshow (@var{i}) |
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22 ## @deftypefnx {Function File} {} imshow (@var{x}, @var{map}) |
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23 ## @deftypefnx {Function File} {} imshow (@var{i}, @var{n}) |
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24 ## @deftypefnx {Function File} {} imshow (@var{r}, @var{g}, @var{b}) |
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25 ## Display an image. |
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26 ## |
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27 ## @code{imshow (@var{x})} displays an image @var{x}. |
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28 ## The numerical class of the image determines its bit-depth: 1 for |
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29 ## @code{logical}, 8 for @code{uint8} and @code{logical}, and 16 for |
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30 ## @code{double} or @code{uint16}. If @var{x} has dimensions MxNx3, the |
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31 ## three matrices represent the red, green and blue components of the |
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32 ## image. |
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33 ## |
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34 ## @code{imshow (@var{x}, @var{map})} displays an indexed image using the |
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35 ## specified colormap. |
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36 ## |
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37 ## @code{imshow (@var{i}, @var{n})} displays a gray scale intensity image of |
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38 ## N levels. |
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39 ## |
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40 ## @code{imshow (@var{r}, @var{g}, @var{b})} displays an RGB image. |
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41 ## |
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42 ## The character string @code{"truesize"} can always be used as an |
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43 ## optional final argument to prevent automatic zooming of the image. |
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44 ## @end deftypefn |
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45 ## @seealso{image, imagesc, colormap, gray2ind, and rgb2ind} |
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46 |
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47 ## Author: Tony Richardson <arichard@stark.cc.oh.us> |
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48 ## Created: July 1994 |
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49 ## Adapted-By: jwe |
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50 |
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51 function imshow (varargin) |
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52 |
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53 usage_str = "imshow (x) or imshow (x, map) or imshow (i, N) or imshow (r, g, b)"; |
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54 |
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55 if (nargin == 0 || nargin > 4) |
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56 usage (usage_str); |
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57 endif |
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58 |
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59 ## Count nr of matrix arguments. |
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60 mvars = 0; |
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61 while (mvars < nargin && ismatrix (varargin{mvars+1})) |
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62 mvars++; |
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63 endwhile |
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64 |
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65 if (mvars < 1 || mvars > 3) |
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66 usage (usage_str); |
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67 endif |
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68 |
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69 ## Determine image depth |
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70 imclass = class (varargin{1}); |
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71 s = __im_numeric_limits__ (imclass); |
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72 if (!isfield (s, "max")) |
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73 error ("imshow: cannot handle image class '%s'", imclass); |
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74 endif |
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75 |
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76 ## Maximum bit-depth is 16 |
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77 if (s.max > 65535) |
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78 s.max = 65535; |
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79 endif |
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80 |
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81 imdepth = log (s.max+1) / log (2); |
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82 if (imdepth - floor (imdepth) != 0) |
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83 error ("imshow: cannot determine image colour depth"); |
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84 endif |
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85 |
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86 ## Remove complex parts of arguments |
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87 realwarning = false; |
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88 for i = 1:mvars |
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89 if (iscomplex (varargin{i})) |
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90 if (!realwarning) |
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91 warning ("imshow: displaying real part of complex image"); |
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92 realwarning = true; |
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93 endif |
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94 varargin{i} = real (varargin{i}); |
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95 endif |
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96 endfor |
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97 |
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98 ## Pack r,g,b image into ND-matrix if necessary |
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99 if (mvars == 3) |
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100 I = []; |
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101 try |
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102 I = cat (3, varargin{1:3}); |
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103 catch |
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104 error ("imshow: r, g and b matrix dimensions must agree"); |
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105 end_try_catch |
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106 else |
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107 I = varargin{1}; |
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108 endif |
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109 I = double (I); |
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110 |
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111 ## Is the image specified as MxNx3 colour? |
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112 iscolour = false; |
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113 if (size (I,3) == 3) |
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114 iscolour = true; |
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115 endif |
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116 |
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117 ## Is the image indexed? |
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118 isindexed = false; |
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119 if (mvars == 2) |
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120 isindexed = true; |
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121 if (iscolour) |
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122 error ("imshow: cannot provide colour image and colourmap"); |
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123 endif |
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124 endif |
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125 |
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126 ## Scale images of class "double" appropriately |
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127 if (!isindexed) |
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128 if (strcmp (imclass, "double") == 1) |
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129 if (max (I(:)) <= 1) |
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130 ## image in [0-1]; scale to [0 - 2^imdepth] |
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131 I = I * 2^imdepth; |
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132 else |
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133 ## image outside [0-1]; this is unexpected: scale to [0 - 2^imdepth] |
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134 I = I / max (I(:)) * 2^imdepth; |
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135 endif |
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136 endif |
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137 endif |
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138 |
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139 ## Generate colour map |
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140 if (isindexed) |
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141 M = varargin{2}; |
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142 if (isscalar (M)) |
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143 M = gray (M); |
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144 endif |
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145 elseif (iscolour) |
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146 I = I / 2^imdepth; |
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147 [I, M] = rgb2ind (I(:,:,1), I(:,:,2), I(:,:,3)); |
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148 else |
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149 I = I+1; ## index into colourmap |
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150 M = gray (2^imdepth); |
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151 endif |
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152 |
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153 ## Check for "truesize". |
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154 zoom = []; |
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155 for i = mvars+1:nargin |
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156 if (isstr (varargin{i}) && strcmp (varargin{i}, "truesize")) |
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157 zoom = 1; |
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158 endif |
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159 endfor |
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160 |
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161 colormap (M); |
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162 image (I, zoom); |
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163 |
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164 endfunction |
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165 |
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166 function s = __im_numeric_limits__ (cname) |
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167 s = struct (); |
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168 switch (cname) |
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169 case ("double") |
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170 s.max = realmax; |
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171 case ("char") |
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172 s.max = 255; |
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173 case ("logical") |
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174 s.max = 1; |
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175 otherwise |
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176 try |
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177 s.max = double (intmax (cname)); |
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178 catch |
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179 end_try_catch |
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180 endswitch |
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181 endfunction |
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182 |
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183 %!error imshow () # no arguments |
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184 %!error imshow (1, 2, 3, 4, 5) # too many arguments |
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185 %!error imshow ([1,2], [2,3], [3,4], [4,5]) # too many matrix arguments |
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186 %!error imshow ("image.png") # filename not accepted as argument |
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187 |
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188 %!demo |
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189 %! imshow (loadimage ("default.img")); |
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190 |
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191 %!demo |
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192 %! I = loadimage ("default.img"); |
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193 %! imshow (I, "truesize") |
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194 |
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195 %!demo |
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196 %! [I, M] = loadimage ("default.img"); |
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197 %! imshow (I, M); |
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198 |
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199 %!demo |
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200 %! [I, M] = loadimage ("default.img"); |
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201 %! imshow (I, I*0.5, I*0.8); |
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202 |
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203 %!demo |
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204 %! [I, M] = loadimage ("default.img"); |
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205 %! X = []; |
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206 %! X = cat (3, X, I*0.8); |
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207 %! X = cat (3, X, I*0.8); |
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208 %! X = cat (3, X, I); |
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209 %! imshow (X); |
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210 |
