41 lines
1.3 KiB
Groff
41 lines
1.3 KiB
Groff
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.TH CONVERSIONS 3 "28 June 1990"
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.SH NAME
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im_scale, im_scaleps \- scale an image to unsigned char image
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.SH SYNOPSIS
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#include <vips/vips.h>
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int im_scale(in, out)
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.br
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IMAGE *in, *out;
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int im_scaleps(in, out)
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.br
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IMAGE *in, *out;
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.SH DESCRIPTION
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These functions scale a non-complex image to a displayable
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byte (unsigned char) image.
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im_scale() scales the image held by image descriptor to a byte (unsigned char)
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image and writes the result on the image descriptor out. Sizes and the number
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of the bands of out are identical to those of input.
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Input image should be non complex and can have any number of channels.
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The output is scaled between 0 and 255; if the image is multiband the maximum
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value of all channels is set to 255 and the minimum to 0. In all cases,
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rounding is performed by adding .5 to the scaled values.
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.B im_scaleps()
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scales to 0 - 255 by mapping each pixel through the equation
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log10(1.0 + pow(x, 0.25))
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and then multiplying by a factor so that the image maximum is 255.
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This transformation highlights both low and high spatial
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frequencies in the power spectrum.
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The images produced by this non-linear transformation are only
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for display and not for further processing.
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.SH RETURN VALUE
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Each function returns 0 on success and -1 on error.
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.SH SEE ALSO
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im_any2c(3), im_c2amph(3), im_clip(3)
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