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comparison scripts/image/gray2ind.m @ 15714:b1cd65881592

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Clean up scripts in image directory. Use Octave coding conventions. Redo docstrings. Add %!tests. * brighten.m: Put input validation first. Use iscolormap to simplify input checking. * cmunique.m: Use faster method of validating input class. * colormap.m: Tweak docstring. Improve input validation. * contrast.m: Tweak docstring. Use cmap instead of map as variable name for clarity. * gray2ind.m: Wrap long lines. Use faster method of validating input class. Delete unreachable code for n>65536. * hsv2rgb.m: Use faster method of validating input class. * imwrite.m: Tweak FIXME notes. * ind2gray.m: Use correct caller name for ind2x. Update %!tests with new 2-input calling convention. * ind2rgb.m: Tweak docstring. Update %!tests with new 2-input calling convention. * iscolormap.m: Tweak docstring. Re-order validation tests. * ntsc2rgb.m: Use faster method of validating input class. Better input validation. Add %!tests. * private/ind2x.m: Use more descriptive variable names. * rgb2hsv.m: Tweak docstring. Use faster method of validating input class. * rgb2ind.m: Tweak docstring. Wrap long lines. * rgb2ntsc.m: Use faster method of validating input class. Improve input validation. Add %!tests. * rgbplot.m: Match variable names in docstring to those in function prototype.
author Rik <rik@octave.org>
date Sun, 02 Dec 2012 10:02:57 -0800
parents a1b634240352
children 3dec0a57ab55
comparison
equal deleted inserted replaced
15713:168e380c8f18 15714:b1cd65881592
26 ## 26 ##
27 ## The indexed image will consist of @var{n} different intensity values. 27 ## The indexed image will consist of @var{n} different intensity values.
28 ## If not given @var{n} defaults to 64 for grayscale images or 2 for 28 ## If not given @var{n} defaults to 64 for grayscale images or 2 for
29 ## binary black and white images. 29 ## binary black and white images.
30 ## 30 ##
31 ## The output @var{img} is of class uint8 or uint 16 if @var{n} is less than or 31 ## The output @var{img} is of class uint8 if @var{n} is less than or
32 ## equal to 256 or 65536 respectively. Otherwise, the output is of class double. 32 ## equal to 256; Otherwise the return class is uint16.
33 ## @seealso{ind2gray, rgb2ind} 33 ## @seealso{ind2gray, rgb2ind}
34 ## @end deftypefn 34 ## @end deftypefn
35 35
36 ## Author: Tony Richardson <arichard@stark.cc.oh.us> 36 ## Author: Tony Richardson <arichard@stark.cc.oh.us>
37 ## Created: July 1994 37 ## Created: July 1994
44 elseif (! isreal (I) || issparse (I)) 44 elseif (! isreal (I) || issparse (I))
45 error ("gray2ind: I must be a grayscale or binary image"); 45 error ("gray2ind: I must be a grayscale or binary image");
46 elseif (! isscalar (n) || n < 1 || n > 65536) 46 elseif (! isscalar (n) || n < 1 || n > 65536)
47 error ("gray2ind: N must be a positive integer in the range [1, 65536]"); 47 error ("gray2ind: N must be a positive integer in the range [1, 65536]");
48 elseif (! ismatrix (I) || ndims (I) != 2) 48 elseif (! ismatrix (I) || ndims (I) != 2)
49 error ("gray2ind: first input argument must be a gray scale image"); 49 error ("gray2ind: I must be a grayscale or binary image");
50 endif 50 endif
51 51
52 ## default n is different if image is logical 52 ## default n is different if image is logical
53 if (nargin == 1 && islogical (I)) 53 if (nargin == 1 && islogical (I))
54 n = 2; 54 n = 2;
55 endif 55 endif
56 56
57 if (! isscalar (n) || n < 0)
58 error ("gray2ind: second input argument must be a positive integer");
59 endif
60
61 cls = class (I); 57 cls = class (I);
62 if (! any (isa (I, {"logical", "uint8", "uint16", "int16", "single", "double"}))) 58 if (! any (strcmp (cls, {"logical", "uint8", "uint16", "int16", "single", "double"})))
63 error ("gray2ind: invalid data type '%s'", cls); 59 error ("gray2ind: invalid data type '%s'", cls);
64 elseif (isfloat (I) && (min (I(:) < 0) || max (I(:) > 1))) 60 elseif (isfloat (I) && (min (I(:) < 0) || max (I(:) > 1)))
65 error ("gray2ind: floating point images may only contain values between 0 and 1"); 61 error ("gray2ind: floating point images may only contain values between 0 and 1");
66 endif 62 endif
67 63
73 scale = double (intmax (cls)) - low; 69 scale = double (intmax (cls)) - low;
74 I = double (I) - low; 70 I = double (I) - low;
75 else 71 else
76 scale = 1; 72 scale = 1;
77 endif 73 endif
74 I *= (n-1)/scale;
75
78 ## Note: no separate call to round () necessary because 76 ## Note: no separate call to round () necessary because
79 ## type conversion does that automatically. 77 ## type conversion does that automatically.
80 I = I * ((n-1)/scale);
81 if (n < 256) 78 if (n < 256)
82 I = uint8 (I); 79 I = uint8 (I);
83 elseif (n < 65536) 80 else
84 I = uint16 (I); 81 I = uint16 (I);
85 else
86 ## if uint16 is not enough, we return double in which case index
87 ## values should start at 1.
88 I = round (I) + 1;
89 endif 82 endif
83
90 endfunction 84 endfunction
85
91 86
92 %!assert (gray2ind ([0 0.25 0.5 1]), uint8 ([0 16 32 63])) 87 %!assert (gray2ind ([0 0.25 0.5 1]), uint8 ([0 16 32 63]))
93 %!assert (gray2ind ([0 0.25 0.5 1], 400), uint16 ([0 100 200 399])) 88 %!assert (gray2ind ([0 0.25 0.5 1], 400), uint16 ([0 100 200 399]))
94 %!assert (gray2ind (logical ([1 0 0 1])), uint8 ([1 0 0 1])) 89 %!assert (gray2ind (logical ([1 0 0 1])), uint8 ([1 0 0 1]))
95 %!assert (gray2ind (uint8 ([0 64 128 192 255])), uint8 ([0 16 32 47 63])) 90 %!assert (gray2ind (uint8 ([0 64 128 192 255])), uint8 ([0 16 32 47 63]))