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Diffstat (limited to 'src/qcam/assets/shader/bayer_1x_packed.frag')
| -rw-r--r-- | src/qcam/assets/shader/bayer_1x_packed.frag | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/src/qcam/assets/shader/bayer_1x_packed.frag b/src/qcam/assets/shader/bayer_1x_packed.frag new file mode 100644 index 00000000..d36db8a2 --- /dev/null +++ b/src/qcam/assets/shader/bayer_1x_packed.frag @@ -0,0 +1,185 @@ +/* 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 + +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_X * center_pixel.x + 0.02; + + const float threshold_l = 0.127 /* fract(BPP_X) * 0.5 + 0.02 */; + const float threshold_h = 0.625 /* 1.0 - fract(BPP_X) * 1.5 */; + + 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 + * of the current group of the pixels, move xcoords[1] one + * byte forward. + */ + xcoords[1] += (fract_x > threshold_h) ? tex_step.x : 0.0; + + vec2 alternate = mod(center_pixel.xy + tex_bayer_first_red, 2.0); + bool even_col = alternate.x < 1.0; + bool even_row = alternate.y < 1.0; + + /* + * We need to sample the central pixel and the ones with offset + * of -1 to +1 pixel in both X and Y directions. Let's name these + * pixels as below, where C is the central pixel: + * + * +----+----+----+----+ + * | \ x| | | | + * |y \ | -1 | 0 | +1 | + * +----+----+----+----+ + * | +1 | D2 | A1 | D3 | + * +----+----+----+----+ + * | 0 | B0 | C | B1 | + * +----+----+----+----+ + * | -1 | D0 | A0 | D1 | + * +----+----+----+----+ + * + * In the below equations (0,-1).r means "r component of the texel + * shifted by -tex_step.y from the center_bytes one" etc. + * + * In the even row / even column (EE) case the colour values are: + * R = C = (0,0).r, + * G = (A0 + A1 + B0 + B1) / 4.0 = + * ( (0,-1).r + (0,1).r + (-1,0).r + (1,0).r ) / 4.0, + * B = (D0 + D1 + D2 + D3) / 4.0 = + * ( (-1,-1).r + (1,-1).r + (-1,1).r + (1,1).r ) / 4.0 + * + * For even row / odd column (EO): + * R = (B0 + B1) / 2.0 = ( (-1,0).r + (1,0).r ) / 2.0, + * G = C = (0,0).r, + * B = (A0 + A1) / 2.0 = ( (0,-1).r + (0,1).r ) / 2.0 + * + * For odd row / even column (OE): + * R = (A0 + A1) / 2.0 = ( (0,-1).r + (0,1).r ) / 2.0, + * G = C = (0,0).r, + * B = (B0 + B1) / 2.0 = ( (-1,0).r + (1,0).r ) / 2.0 + * + * For odd row / odd column (OO): + * R = (D0 + D1 + D2 + D3) / 4.0 = + * ( (-1,-1).r + (1,-1).r + (-1,1).r + (1,1).r ) / 4.0, + * G = (A0 + A1 + B0 + B1) / 4.0 = + * ( (0,-1).r + (0,1).r + (-1,0).r + (1,0).r ) / 4.0, + * B = C = (0,0).r + */ + + /* + * Fetch the values and precalculate the terms: + * patterns.x = (A0 + A1) / 2.0 + * patterns.y = (B0 + B1) / 2.0 + * patterns.z = (A0 + A1 + B0 + B1) / 4.0 + * patterns.w = (D0 + D1 + D2 + D3) / 4.0 + */ + #define fetch(x, y) texture2D(tex_y, vec2(x, y)).r + + float C = texture2D(tex_y, center_bytes).r; + vec4 patterns = vec4( + fetch(center_bytes.x, ycoords[0]), /* A0: (0,-1) */ + fetch(xcoords[0], center_bytes.y), /* B0: (-1,0) */ + fetch(xcoords[0], ycoords[0]), /* D0: (-1,-1) */ + fetch(xcoords[1], ycoords[0])); /* D1: (1,-1) */ + vec4 temp = vec4( + fetch(center_bytes.x, ycoords[1]), /* A1: (0,1) */ + fetch(xcoords[1], center_bytes.y), /* B1: (1,0) */ + fetch(xcoords[1], ycoords[1]), /* D3: (1,1) */ + fetch(xcoords[0], ycoords[1])); /* D2: (-1,1) */ + patterns = (patterns + temp) * 0.5; + /* .x = (A0 + A1) / 2.0, .y = (B0 + B1) / 2.0 */ + /* .z = (D0 + D3) / 2.0, .w = (D1 + D2) / 2.0 */ + patterns.w = (patterns.z + patterns.w) * 0.5; + patterns.z = (patterns.x + patterns.y) * 0.5; + + rgb = even_col ? + (even_row ? + vec3(C, patterns.zw) : + vec3(patterns.x, C, patterns.y)) : + (even_row ? + vec3(patterns.y, C, patterns.x) : + vec3(patterns.wz, C)); + + gl_FragColor = vec4(rgb, 1.0); +} |