1 .TH CROP 1
2 .SH NAME
3 crop, iconv \- frame, crop, and convert image
4 .SH SYNOPSIS
5 .B crop
6 [
7 .BI -c
8 .I red
9 .I green
10 .I blue
11 ]
12 [
13 .B -i
14 .I n
15 |
16 .B -x
17 .I dx
18 |
19 .B -y
20 .I dy
21 |
22 .B -r
23 .I minx
24 .I miny
25 .I maxx
26 .I maxy
27 ]
28 [
29 .B -t
30 .I tx
31 .I ty
32 ]
33 [
34 .B -b
35 .I red
36 .I green
37 .I blue
38 ]
39 [
40 .I file
41 ]
42 .PP
43 .B iconv
44 [
45 .B -u
46 ] [
47 .B -c
48 .I chandesc
49 ]
50 [
51 .I file
52 ]
53 .SH DESCRIPTION
54 .I Crop
55 reads an
56 .MR image (7)
57 file (default standard input), crops it, and writes it as a compressed
58 .MR image (7)
59 file to standard output.
60 There are two ways to specify a crop, by color value or by geometry.
61 They may be combined in a single run of
62 .IR crop ,
63 in which case the color value crop will be done first.
64 .PP
65 The
66 .B -c
67 option takes a red-green-blue triplet as described in
68 .MR color (3) .
69 (For example, white
70 is
71 .B 255
72 .B 255
73 .BR 255 .)
74 The corresponding color is used as a value to be cut from the outer
75 edge of the picture; that is, the image is cropped to remove the maximal
76 outside rectangular strip in which every pixel has the specified color.
77 .PP
78 The
79 .B -i
80 option insets the image rectangle by a constant amount,
81 .IR n ,
82 which may be negative to generate extra space around the image.
83 The
84 .B -x
85 and
86 .B -y
87 options are similar, but apply only to the
88 .I x
89 or
90 .I y
91 coordinates of the image.
92 .PP
93 The
94 .B -r
95 option specifies an exact rectangle.
96 .PP
97 The 
98 .B -t
99 option specifies that the image's coordinate system should
100 be translated by
101 .IR tx ,
102 .IR ty
103 as the last step of processing.
104 .PP
105 The
106 .B -b
107 option specifies a background color to be used to fill around the image
108 if the cropped image is larger than the original, such as if the
109 .B -i
110 option is given a negative argument.
111 This can be used to draw a monochrome frame around the image.
112 The default color is black.
113 .PP
114 .I Iconv
115 changes the format of pixels in the image
116 .I file
117 (default standard input) and writes the resulting image to standard output.
118 Pixels in the image are converted according to the channel descriptor
119 .IR chandesc ,
120 (see
121 .MR image (7) ).
122 For example, to convert a 4-bit-per-pixel grey-scale image to an 8-bit-per-pixel
123 color-mapped image,
124 .I chandesc
125 should be
126 .BR m8 .
127 If
128 .I chandesc
129 is not given, the format is unchanged.
130 The output image is by default compressed; the
131 .B -u
132 option turns off the compression.
133 .SH EXAMPLE
134 To crop white edges off the picture and add a ten-pixel pink border,
135 .IP
136 .EX
137 crop -c 255 255 255 -i -10 -b 255 150 150 imagefile > cropped
138 .EE
139 .SH SOURCE
140 .B \*9/src/cmd/draw/crop.c
141 .SH SEE ALSO
142 .MR image (7) ,
143 .MR color (3)
144 .SH BUGS
145 .I Iconv
146 should be able to do Floyd-Steinberg error diffusion or dithering
147 when converting to small image depths.