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/* SPDX-License-Identifier: BSD-2-Clause */
/*
* Based on the code from http://jgt.akpeters.com/papers/McGuire08/
*
* Efficient, High-Quality Bayer Demosaic Filtering on GPUs
*
* Morgan McGuire
*
* This paper appears in issue Volume 13, Number 4.
* ---------------------------------------------------------
* Copyright (c) 2008, Morgan McGuire. All rights reserved.
*
*
* Modified by Linaro Ltd for 10/12-bit packed vs 8-bit raw Bayer format,
* and for simpler demosaic algorithm.
* Copyright (C) 2020, Linaro
*
* bayer_1x_packed.frag - Fragment shader code for raw Bayer 10-bit and 12-bit
* packed formats
*/
#ifdef GL_ES
precision mediump float;
#endif
/*
* These constants are used to select the bytes containing the HS part of
* the pixel value:
* BPP - bytes per pixel,
* THRESHOLD_L = fract(BPP) * 0.5 + 0.02
* THRESHOLD_H = 1.0 - fract(BPP) * 1.5 + 0.02
* Let X is the x coordinate in the texture measured in bytes (so that the
* range is from 0 to (stride_-1)) aligned on the nearest pixel.
* E.g. for RAW10P:
* -------------+-------------------+-------------------+--
* pixel No | 0 1 2 3 | 4 5 6 7 | ...
* -------------+-------------------+-------------------+--
* byte offset | 0 1 2 3 4 | 5 6 7 8 9 | ...
* -------------+-------------------+-------------------+--
* X | 0.0 1.25 2.5 3.75 | 5.0 6.25 7.5 8.75 | ...
* -------------+-------------------+-------------------+--
* If fract(X) < THRESHOLD_L then the previous byte contains the LS
* bits of the pixel values and needs to be skipped.
* If fract(X) > THRESHOLD_H then the next byte contains the LS bits
* of the pixel values and needs to be skipped.
*/
#if defined(RAW10P)
#define BPP 1.25
#define THRESHOLD_L 0.14
#define THRESHOLD_H 0.64
#elif defined(RAW12P)
#define BPP 1.5
#define THRESHOLD_L 0.27
#define THRESHOLD_H 0.27
#else
#error Invalid raw format
#endif
varying vec2 textureOut;
/* the texture size in pixels */
uniform vec2 tex_size;
uniform vec2 tex_step;
uniform vec2 tex_bayer_first_red;
uniform sampler2D tex_y;
void main(void)
{
vec3 rgb;
/*
* center_bytes holds the coordinates of the MS byte of the pixel
* being sampled on the [0, stride-1/height-1] range.
* center_pixel holds the coordinates of the pixel being sampled
* on the [0, width/height-1] range.
*/
vec2 center_bytes;
vec2 center_pixel;
/*
* x- and y-positions of the adjacent pixels on the [0, 1] range.
*/
vec2 xcoords;
vec2 ycoords;
/*
* The coordinates passed to the shader in textureOut may point
* to a place in between the pixels if the texture format doesn't
* match the image format. In particular, MIPI packed raw Bayer
* formats don't have a matching texture format.
* In this case align the coordinates to the left nearest pixel
* by hand.
*/
center_pixel = floor(textureOut * tex_size);
center_bytes.y = center_pixel.y;
/*
* Add a small number (a few mantissa's LSBs) to avoid float
* representation issues. Maybe paranoic.
*/
center_bytes.x = BPP * center_pixel.x + 0.02;
float fract_x = fract(center_bytes.x);
/*
* The below floor() call ensures that center_bytes.x points
* at one of the bytes representing the 8 higher bits of
* the pixel value, not at the byte containing the LS bits
* of the group of the pixels.
*/
center_bytes.x = floor(center_bytes.x);
center_bytes *= tex_step;
xcoords = center_bytes.x + vec2(-tex_step.x, tex_step.x);
ycoords = center_bytes.y + vec2(-tex_step.y, tex_step.y);
/*
* If xcoords[0] points at the byte containing the LS bits
* of the previous group of the pixels, move xcoords[0] one
* byte back.
*/
xcoords[0] += (fract_x < THRESHOLD_L) ? -tex_step.x : 0.0;
/*
* If xcoords[1] points at the byte containing the LS bits
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