forked from Archive/PX4-Autopilot
104 lines
4.4 KiB
C
104 lines
4.4 KiB
C
/****************************************************************************
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* graphics/color/nxglib_rgb2yuv.c
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*
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* Copyright (C) 2008, 2011 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <debug.h>
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#include <fixedmath.h>
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#include <nuttx/nx/nxglib.h>
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/****************************************************************************
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* Pre-Processor Definitions
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****************************************************************************/
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#define b16_P0813 0x000014d0 /* 0.0813 */
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#define b16_P1140 0x00001d2f /* 0.1140 */
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#define b16_P1687 0x00002b30 /* 0.1687 */
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#define b16_P2990 0x00004c8b /* 0.2990 */
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#define b16_P3313 0x000054d0 /* 0.3313 */
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#define b16_P4187 0x00006b30 /* 0.4187 */
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#define b16_P5000 0x00008000 /* 0.5000 */
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#define b16_P5870 0x00009646 /* 0.5870 */
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#define b16_128P0 0x00800000 /* 128.0 */
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxgl_rgb2yuv
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*
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* Description:
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* Convert 8-bit RGB triplet to 8-bit YUV triplet
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*
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****************************************************************************/
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void nxgl_rgb2yuv(uint8_t r, uint8_t g, uint8_t b,
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uint8_t *y, uint8_t *u, uint8_t *v)
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{
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/* Per the JFIF specification:
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*
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* Y = (0.2990 * R) + (0.5870 * G) + (0.1140 * B)
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* U = 128 - (0.1687 * R) - (0.3313 * G) + (0.5000 * B)
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* V = 128 + (0.5000 * R) - (0.4187 * G) - (0.0813 * B);
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*/
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*y = (uint8_t)b16toi(b16muli(b16_P2990, r) + b16muli(b16_P5870, g) + b16muli(b16_P1140, b));
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*u = (uint8_t)b16toi(b16_128P0 - b16muli(b16_P1687, r) - b16muli(b16_P3313, g) + b16muli(b16_P5000, b));
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*v = (uint8_t)b16toi(b16_128P0 + b16muli(b16_P5000, r) - b16muli(b16_P4187, g) - b16muli(b16_P0813, b));
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}
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