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[opticflow] Resize function fix: keep color together and also keep working with downsample=1 (copy)

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dewagter
2015-01-14 09:35:33 +01:00
parent 348e825a2a
commit cacecab21b
1 changed files with 20 additions and 7 deletions
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sw/airborne/modules/computer_vision/cv/resize.h
+20 -7
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@@ -23,26 +23,39 @@
#include <stdint.h>
#include "image.h"
/** Simplified high-speed low CPU downsample function without averaging
*
* downsample factor must be 1, 2, 4, 8 ... 2^X
* image of typ UYVY expected. Only one color UV per 2 pixels
*
* we keep the UV color of the first pixel pair
* and sample the intensity evenly 1-3-5-7-... or 1-5-9-...
*
* input: u1y1 v1y2 u3y3 v3y4 u5y5 v5y6 u7y7 v7y8 ...
* downsample=1 u1y1 v1y2 u3y3 v3y4 u5y5 v5y6 u7y7 v7y8 ...
* downsample=2 u1y1v1 (skip2) y3 (skip2) u5y5v5 (skip2 y7 (skip2) ...
* downsample=4 u1y1v1 (skip6) y5 (skip6) ...
*/
inline void resize_uyuv(struct img_struct *input, struct img_struct *output, int downsample);
inline void resize_uyuv(struct img_struct *input, struct img_struct *output, int downsample)
{
uint8_t *source = input->buf;
uint8_t *dest = output->buf;
int pixelskip = downsample - 1;
int pixelskip = (downsample - 1) * 2;
for (int y = 0; y < output->h; y++) {
for (int x = 0; x < output->w; x += 2) {
// YUYV
*dest++ = *source++; // U
*dest++ = *source++; // Y
// now skip 3 pixels
source += (pixelskip + 1) * 2;
*dest++ = *source++; // U
*dest++ = *source++; // V
source += (pixelskip - 1) * 2;
source += pixelskip;
*dest++ = *source++; // Y
source += pixelskip;
}
// skip 3 rows
source += pixelskip * input->w * 2;
// read 1 in every 'downsample' rows, so skip (downsample-1) rows after reading the first
source += (downsample-1) * input->w * 2;
}
}