1nearblack(1) General Commands Manual nearblack(1)
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6 nearblackConvert nearly black/white borders to black.
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9 nearblack [-of format] [-white | [-color c1,c2,c3...cn]*] [-near dist] [-nb non_black_pixels]
10 [-setalpha] [-setmask] [-o outfile] [-q] [-co "NAME=VALUE"]* infile
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13 This utility will scan an image and try to set all pixels that are
14 nearly or exactly black, white or one or more custom colors around the
15 collar to black or white. This is often used to 'fix up' lossy
16 compressed air photos so that color pixels can be treated as
17 transparent when mosaicing.
18 -o outfile:
20 The name of the output file to be created.
21 -of format:
23 (GDAL 1.8.0 or later) Select the output format. Starting with GDAL
24 2.3, if not specified, the format is guessed from the extension
25 (previously was ERDAS Imagine .img). Use the short format name
26 (GTiff for GeoTIFF for example).
27 -co 'NAME=VALUE':
29 (GDAL 1.8.0 or later) Passes a creation option to the output format
30 driver. Multiple -co options may be listed. See format specific
31 documentation for legal creation options for each format. Only
32 valid when creating a new file
33 -white:
35 Search for nearly white (255) pixels instead of nearly black
36 pixels.
37 -color c1,c2,c3...cn:
39 (GDAL >= 1.9.0) Search for pixels near the specified color. May be
40 specified multiple times. When -color is specified, the pixels that
41 are considered as the collar are set to 0.
42 -near dist:
44 Select how far from black, white or custom colors the pixel values
45 can be and still considered near black, white or custom color.
46 Defaults to 15.
47 -nb non_black_pixels:
49 number of non-black pixels that can be encountered before the
50 giving up search inwards. Defaults to 2.
51 -setalpha:
53 (GDAL 1.8.0 or later) Adds an alpha band if the output file is
54 specified and the input file has 3 bands, or sets the alpha band of
55 the output file if it is specified and the input file has 4 bands,
56 or sets the alpha band of the input file if it has 4 bands and no
57 output file is specified. The alpha band is set to 0 in the image
58 collar and to 255 elsewhere.
59 -setmask:
61 (GDAL 1.8.0 or later) Adds a mask band to the output file, or adds
62 a mask band to the input file if it does not already have one and
63 no output file is specified. The mask band is set to 0 in the image
64 collar and to 255 elsewhere.
65 -q:
67 (GDAL 1.8.0 or later) Suppress progress monitor and other non-error
68 output.
69 infile:
71 The input file. Any GDAL supported format, any number of bands,
72 normally 8bit Byte bands.
73 The algorithm processes the image one scanline at a time. A scan 'in'
75 is done from either end setting pixels to black or white until at least
76 'non_black_pixels' pixels that are more than 'dist' gray levels away
77 from black, white or custom colors have been encountered at which point
78 the scan stops. The nearly black, white or custom color pixels are set
79 to black or white. The algorithm also scans from top to bottom and from
80 bottom to top to identify indentations in the top or bottom.
81 The processing is all done in 8bit (Bytes).
83 If the output file is omitted, the processed results will be written
85 back to the input file - which must support update.
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88 Starting with GDAL 2.1, this utility is also callable from C with
89 GDALNearblack().
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92 Frank Warmerdam warmerdam@pobox.com
93GDAL Wed Oct 3 2018 nearblack(1)