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- /****************************************************************************
- * libs/libnx/nxglib/nxglib_rgb2yuv.c
- *
- * Copyright (C) 2008, 2011, 2013 Gregory Nutt. All rights reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <stdint.h>
- #include <debug.h>
- #include <fixedmath.h>
- #include <nuttx/nx/nxglib.h>
- /****************************************************************************
- * Pre-Processor Definitions
- ****************************************************************************/
- #define b16_P0813 0x000014d0 /* 0.0813 */
- #define b16_P1140 0x00001d2f /* 0.1140 */
- #define b16_P1687 0x00002b30 /* 0.1687 */
- #define b16_P2990 0x00004c8b /* 0.2990 */
- #define b16_P3313 0x000054d0 /* 0.3313 */
- #define b16_P4187 0x00006b30 /* 0.4187 */
- #define b16_P5000 0x00008000 /* 0.5000 */
- #define b16_P5870 0x00009646 /* 0.5870 */
- #define b16_128P0 0x00800000 /* 128.0 */
- /****************************************************************************
- * Private Types
- ****************************************************************************/
- /****************************************************************************
- * Private Function Prototypes
- ****************************************************************************/
- /****************************************************************************
- * Private Data
- ****************************************************************************/
- /****************************************************************************
- * Private Functions
- ****************************************************************************/
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: nxgl_rgb2yuv
- *
- * Description:
- * Convert 8-bit RGB triplet to 8-bit YUV triplet
- *
- ****************************************************************************/
- void nxgl_rgb2yuv(uint8_t r, uint8_t g, uint8_t b,
- uint8_t *y, uint8_t *u, uint8_t *v)
- {
- /* Per the JFIF specification:
- *
- * Y = (0.2990 * R) + (0.5870 * G) + (0.1140 * B)
- * U = 128 - (0.1687 * R) - (0.3313 * G) + (0.5000 * B)
- * V = 128 + (0.5000 * R) - (0.4187 * G) - (0.0813 * B);
- */
- *y = (uint8_t)b16toi(b16muli(b16_P2990, r) + b16muli(b16_P5870, g) + b16muli(b16_P1140, b));
- *u = (uint8_t)b16toi(b16_128P0 - b16muli(b16_P1687, r) - b16muli(b16_P3313, g) + b16muli(b16_P5000, b));
- *v = (uint8_t)b16toi(b16_128P0 + b16muli(b16_P5000, r) - b16muli(b16_P4187, g) - b16muli(b16_P0813, b));
- }
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