crop.1 (2603B)
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.