/usr/include/astrometry/ctmf.h is in libastrometry-dev 0.70+dfsg-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 | // See util/ctmf.c for copyright & license
#ifndef CTMF_H
#define CTMF_H
#ifdef __cplusplus
extern "C" {
#endif
/**
* \brief Constant-time median filtering
*
* This function does a median filtering of an 8-bit image. The source image is
* processed as if it was padded with zeros. The median kernel is square with
* odd dimensions. Images of arbitrary size may be processed.
*
* To process multi-channel images, you must call this function multiple times,
* changing the source and destination adresses and steps such that each channel
* is processed as an independent single-channel image.
*
* Processing images of arbitrary bit depth is not supported.
*
* The computing time is O(1) per pixel, independent of the radius of the
* filter. The algorithm's initialization is O(r*width), but it is negligible.
* Memory usage is simple: it will be as big as the cache size, or smaller if
* the image is small. For efficiency, the histograms' bins are 16-bit wide.
* This may become too small and lead to overflow as \a r increases.
*
* \param src Source image data.
* \param dst Destination image data. Must be preallocated.
* \param width Image width, in pixels.
* \param height Image height, in pixels.
* \param src_step Distance between adjacent pixels on the same column in
* the source image, in bytes.
* \param dst_step Distance between adjacent pixels on the same column in
* the destination image, in bytes.
* \param r Median filter radius. The kernel will be a 2*r+1 by
* 2*r+1 square.
* \param cn Number of channels. For example, a grayscale image would
* have cn=1 while an RGB image would have cn=3.
* \param memsize Maximum amount of memory to use, in bytes. Set this to
* the size of the L2 cache, then vary it slightly and
* measure the processing time to find the optimal value.
* For example, a 512 kB L2 cache would have
* memsize=512*1024 initially.
*/
void ctmf(
const unsigned char* src, unsigned char* dst,
int width, int height,
int src_step_row, int dst_step_row,
int r, int channels, unsigned long memsize
);
#ifdef __cplusplus
}
#endif
#endif
|