76 lines
2.9 KiB
C
76 lines
2.9 KiB
C
/****************************************************************************
|
|
* libs/libnx/nxglib/nxglib_rgb2yuv.c
|
|
*
|
|
* Licensed to the Apache Software Foundation (ASF) under one or more
|
|
* contributor license agreements. See the NOTICE file distributed with
|
|
* this work for additional information regarding copyright ownership. The
|
|
* ASF licenses this file to you under the Apache License, Version 2.0 (the
|
|
* "License"); you may not use this file except in compliance with the
|
|
* License. You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
* License for the specific language governing permissions and limitations
|
|
* under the License.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* 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 */
|
|
|
|
/****************************************************************************
|
|
* 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));
|
|
}
|