[libcamera-devel,v2,5/5] qcam: viewfinder_gl: Add support for RAW8 Bayer formats

12452 diff mbox series

All the four Bayer orders are supported.

The texture coordinates passed to the fragment shader are ajusted
to point to the nearest pixel in the image. This prevents artifacts
when the image is scaled from the frame resolution to the window size.

Signed-off-by: Andrey Konovalov <andrey.konovalov@linaro.org>
---
 src/qcam/assets/shader/bayer_8.frag | 136 ++++++++++++++++++++++++++++
 src/qcam/assets/shader/bayer_8.vert |  72 +++++++++++++++
 src/qcam/assets/shader/shaders.qrc  |   1 +
 src/qcam/viewfinder_gl.cpp          |  37 +++++++-
 4 files changed, 244 insertions(+), 2 deletions(-)
 create mode 100644 src/qcam/assets/shader/bayer_8.frag
 create mode 100644 src/qcam/assets/shader/bayer_8.vert

Hi Andrey,

Thank you for the patch.

I would also like to thank Morgan for his code.

On Thu, May 27, 2021 at 01:55:11PM +0300, Andrey Konovalov wrote:
> All the four Bayer orders are supported.
> 
> The texture coordinates passed to the fragment shader are ajusted
> to point to the nearest pixel in the image. This prevents artifacts
> when the image is scaled from the frame resolution to the window size.
> 
> Signed-off-by: Andrey Konovalov <andrey.konovalov@linaro.org>
> ---
>  src/qcam/assets/shader/bayer_8.frag | 136 ++++++++++++++++++++++++++++
>  src/qcam/assets/shader/bayer_8.vert |  72 +++++++++++++++
>  src/qcam/assets/shader/shaders.qrc  |   1 +
>  src/qcam/viewfinder_gl.cpp          |  37 +++++++-
>  4 files changed, 244 insertions(+), 2 deletions(-)
>  create mode 100644 src/qcam/assets/shader/bayer_8.frag
>  create mode 100644 src/qcam/assets/shader/bayer_8.vert
> 
> diff --git a/src/qcam/assets/shader/bayer_8.frag b/src/qcam/assets/shader/bayer_8.frag
> new file mode 100644
> index 00000000..d93ef1da
> --- /dev/null
> +++ b/src/qcam/assets/shader/bayer_8.frag
> @@ -0,0 +1,136 @@
> +/* SPDX-License-Identifier: BSD-2-Clause */
> +/*
> +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 to integrate it into libcamera, and to
> +fix the artifacts due to pixel coordinates interpolation.
> +Copyright (C) 2021, Linaro

Would it make sense to import the original version as-is in a patch, and
then add the changes on top ? It would be easier to review them.

> +*/
> +
> +//Pixel Shader

We try to standardize on C-style comments.

> +
> +varying vec2 textureOut;
> +
> +/* The texture size: tex_size.xy is in bytes, tex_size.zw is in pixels */
> +uniform vec4 tex_size;
> +uniform vec2 tex_step;
> +
> +/** Pixel position of the first red pixel in the */
> +/**  Bayer pattern.  [{0,1}, {0, 1}]*/
> +uniform vec2            tex_bayer_first_red;
> +
> +/** Monochrome RGBA or GL_LUMINANCE Bayer encoded texture.*/
> +uniform sampler2D       tex_raw;
> +
> +void main(void) {
> +    #define fetch(x, y) texture2D(tex_raw, vec2(x, y)).r
> +
> +    /** .xy = Pixel being sampled in the fragment shader on the range [0, 1]
> +        .zw = ...on the range [0, sourceSize], offset by firstRed */

For multiblock comments, our coding style is

    /*
     * .xy = Pixel being sampled in the fragment shader on the range [0, 1]
     * .zw = ...on the range [0, sourceSize], offset by firstRed
     */

This being said, if we want to minimize changes with the original, I
would be OK.

> +    vec4            center;
> +
> +    /** center.x + (-2/w, -1/w, 1/w, 2/w); These are the x-positions */
> +    /** of the adjacent pixels.*/
> +    vec4            xCoord;
> +
> +    /** center.y + (-2/h, -1/h, 1/h, 2/h); These are the y-positions */
> +    /** of the adjacent pixels.*/
> +    vec4            yCoord;

Doesn't computing the center, xCoord and yCoord values here defeat the
point of computing them in the vertex shader, where the interpolator
hardware can be used for the computation ?

> +
> +    /* Align the center coordinates to the nearest pixel */
> +    center.zw = floor(textureOut * tex_size.zw);
> +    center.xy = center.zw * tex_step;
> +    center.zw += tex_bayer_first_red;
> +
> +    xCoord = center.x + vec4(-2.0 * tex_step.x,
> +                             -tex_step.x, tex_step.x, 2.0 * tex_step.x);
> +    yCoord = center.y + vec4(-2.0 * tex_step.y,
> +                              -tex_step.y, tex_step.y, 2.0 * tex_step.y);
> +
> +    float C = texture2D(tex_raw, center.xy).r; // ( 0, 0)
> +    const vec4 kC = vec4( 4.0,  6.0,  5.0,  5.0) / 8.0;
> +
> +    // Determine which of four types of pixels we are on.
> +    vec2 alternate = mod(floor(center.zw), 2.0);
> +
> +    vec4 Dvec = vec4(
> +        fetch(xCoord[1], yCoord[1]),  // (-1,-1)
> +        fetch(xCoord[1], yCoord[2]),  // (-1, 1)
> +        fetch(xCoord[2], yCoord[1]),  // ( 1,-1)
> +        fetch(xCoord[2], yCoord[2])); // ( 1, 1)
> +
> +    vec4 PATTERN = (kC.xyz * C).xyzz;
> +
> +    // Can also be a dot product with (1,1,1,1) on hardware where that is
> +    // specially optimized.
> +    // Equivalent to: D = Dvec[0] + Dvec[1] + Dvec[2] + Dvec[3];
> +    Dvec.xy += Dvec.zw;
> +    Dvec.x  += Dvec.y;
> +
> +    vec4 value = vec4(
> +        fetch(center.x, yCoord[0]),   // ( 0,-2)
> +        fetch(center.x, yCoord[1]),   // ( 0,-1)
> +        fetch(xCoord[0], center.y),   // (-2, 0)
> +        fetch(xCoord[1], center.y));  // (-1, 0)
> +
> +    vec4 temp = vec4(
> +        fetch(center.x, yCoord[3]),   // ( 0, 2)
> +        fetch(center.x, yCoord[2]),   // ( 0, 1)
> +        fetch(xCoord[3], center.y),   // ( 2, 0)
> +        fetch(xCoord[2], center.y));  // ( 1, 0)
> +
> +    // Even the simplest compilers should be able to constant-fold these to
> +    // avoid the division.
> +    // Note that on scalar processors these constants force computation of some
> +    // identical products twice.
> +    const vec4 kA = vec4(-1.0, -1.5,  0.5, -1.0) / 8.0;
> +    const vec4 kB = vec4( 2.0,  0.0,  0.0,  4.0) / 8.0;
> +    const vec4 kD = vec4( 0.0,  2.0, -1.0, -1.0) / 8.0;
> +
> +    // Conserve constant registers and take advantage of free swizzle on load
> +    #define kE (kA.xywz)
> +    #define kF (kB.xywz)
> +
> +    value += temp;
> +
> +    // There are five filter patterns (identity, cross, checker,
> +    // theta, phi).  Precompute the terms from all of them and then
> +    // use swizzles to assign to color channels.
> +    //
> +    // Channel   Matches
> +    //   x       cross   (e.g., EE G)
> +    //   y       checker (e.g., EE B)
> +    //   z       theta   (e.g., EO R)
> +    //   w       phi     (e.g., EO R)
> +    #define A (value[0])
> +    #define B (value[1])
> +    #define D (Dvec.x)
> +    #define E (value[2])
> +    #define F (value[3])
> +
> +    // Avoid zero elements. On a scalar processor this saves two MADDs
> +    // and it has no effect on a vector processor.
> +    PATTERN.yzw += (kD.yz * D).xyy;
> +
> +    PATTERN += (kA.xyz * A).xyzx + (kE.xyw * E).xyxz;
> +    PATTERN.xw  += kB.xw * B;
> +    PATTERN.xz  += kF.xz * F;
> +
> +    vec3 rgb = (alternate.y == 0.0) ?
> +        ((alternate.x == 0.0) ?
> +            vec3(C, PATTERN.xy) :
> +            vec3(PATTERN.z, C, PATTERN.w)) :
> +        ((alternate.x == 0.0) ?
> +            vec3(PATTERN.w, C, PATTERN.z) :
> +            vec3(PATTERN.yx, C));
> +    gl_FragColor = vec4(rgb, 1.0);
> +}
> diff --git a/src/qcam/assets/shader/bayer_8.vert b/src/qcam/assets/shader/bayer_8.vert
> new file mode 100644
> index 00000000..26525db7
> --- /dev/null
> +++ b/src/qcam/assets/shader/bayer_8.vert
> @@ -0,0 +1,72 @@

This needs and SPDX license identifier:

/* SPDX-License-Identifier: BSD-2-Clause */

> +/*
> +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.
> +
> +Redistribution and use in source and binary forms, with or without
> +modification, are permitted provided that the following conditions are
> +met:
> +
> +    * Redistributions of source code must retain the above copyright
> +      notice, this list of conditions and the following disclaimer.
> +
> +    * 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.
> +
> +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.

The whole text from "Redistribution ..." to here is conveyed by the SPDX
tag, so you can drop it.

> +*/
> +
> +//Vertex Shader
> +
> +attribute vec4 vertexIn;
> +attribute vec2 textureIn;
> +
> +/* The texture size: tex_size.xy is in bytes, tex_size.zw is in pixels */
> +uniform vec4 tex_size;
> +uniform vec2 tex_step;
> +
> +/** Pixel position of the first red pixel in the */
> +/**  Bayer pattern.  [{0,1}, {0, 1}]*/
> +uniform vec2            tex_bayer_first_red;
> +
> +/** .xy = Pixel being sampled in the fragment shader on the range [0, 1]
> +    .zw = ...on the range [0, sourceSize], offset by firstRed */
> +varying vec4            center;
> +
> +/** center.x + (-2/w, -1/w, 1/w, 2/w); These are the x-positions */
> +/** of the adjacent pixels.*/
> +varying vec4            xCoord;
> +
> +/** center.y + (-2/h, -1/h, 1/h, 2/h); These are the y-positions */
> +/** of the adjacent pixels.*/
> +varying vec4            yCoord;
> +
> +void main(void) {
> +    center.xy = textureIn;
> +    center.zw = textureIn * tex_size.zw + tex_bayer_first_red;
> +
> +    xCoord = center.x + vec4(-2.0 * tex_step.x,
> +                             -tex_step.x, tex_step.x, 2.0 * tex_step.x);
> +    yCoord = center.y + vec4(-2.0 * tex_step.y,
> +                              -tex_step.y, tex_step.y, 2.0 * tex_step.y);
> +
> +    gl_Position = vertexIn;
> +}
> diff --git a/src/qcam/assets/shader/shaders.qrc b/src/qcam/assets/shader/shaders.qrc
> index d76d65c5..79f44a30 100644
> --- a/src/qcam/assets/shader/shaders.qrc
> +++ b/src/qcam/assets/shader/shaders.qrc
> @@ -5,6 +5,7 @@
>  	<file>YUV_2_planes.frag</file>
>  	<file>YUV_3_planes.frag</file>
>  	<file>YUV_packed.frag</file>
> +	<file>bayer_8.frag</file>

Could you please move this after bayer_1x_packed.frag to keep them
alphabetically sorted ?

You're missing bayer_8.vert.

>  	<file>bayer_1x_packed.frag</file>
>  	<file>identity.vert</file>
>  </qresource>
> diff --git a/src/qcam/viewfinder_gl.cpp b/src/qcam/viewfinder_gl.cpp
> index 13ab31aa..ef85e93d 100644
> --- a/src/qcam/viewfinder_gl.cpp
> +++ b/src/qcam/viewfinder_gl.cpp
> @@ -36,6 +36,11 @@ static const QList<libcamera::PixelFormat> supportedFormats{
>  	libcamera::formats::RGBA8888,
>  	libcamera::formats::BGR888,
>  	libcamera::formats::RGB888,
> +	/* Raw Bayer 8-bit */
> +	libcamera::formats::SBGGR8,
> +	libcamera::formats::SGBRG8,
> +	libcamera::formats::SGRBG8,
> +	libcamera::formats::SRGGB8,
>  	/* Raw Bayer 10-bit packed */
>  	libcamera::formats::SBGGR10_CSI2P,
>  	libcamera::formats::SGBRG10_CSI2P,
> @@ -220,6 +225,30 @@ bool ViewFinderGL::selectFormat(const libcamera::PixelFormat &format)
>  		fragmentShaderDefines_.append("#define RGB_PATTERN bgr");
>  		fragmentShaderFile_ = ":RGB.frag";
>  		break;
> +	case libcamera::formats::SBGGR8:
> +		firstRed_.setX(1.0);
> +		firstRed_.setY(1.0);
> +		fragmentShaderFile_ = ":bayer_8.frag";
> +		textureMinMagFilters_ = GL_NEAREST;
> +		break;
> +	case libcamera::formats::SGBRG8:
> +		firstRed_.setX(0.0);
> +		firstRed_.setY(1.0);
> +		fragmentShaderFile_ = ":bayer_8.frag";
> +		textureMinMagFilters_ = GL_NEAREST;
> +		break;
> +	case libcamera::formats::SGRBG8:
> +		firstRed_.setX(1.0);
> +		firstRed_.setY(0.0);
> +		fragmentShaderFile_ = ":bayer_8.frag";
> +		textureMinMagFilters_ = GL_NEAREST;
> +		break;
> +	case libcamera::formats::SRGGB8:
> +		firstRed_.setX(0.0);
> +		firstRed_.setY(0.0);
> +		fragmentShaderFile_ = ":bayer_8.frag";
> +		textureMinMagFilters_ = GL_NEAREST;
> +		break;
>  	case libcamera::formats::SBGGR10_CSI2P:
>  		firstRed_.setX(1.0);
>  		firstRed_.setY(1.0);
> @@ -624,6 +653,10 @@ void ViewFinderGL::doRender()
>  		shaderProgram_.setUniformValue(textureUniformY_, 0);
>  		break;
>  
> +	case libcamera::formats::SBGGR8:
> +	case libcamera::formats::SGBRG8:
> +	case libcamera::formats::SGRBG8:
> +	case libcamera::formats::SRGGB8:
>  	case libcamera::formats::SBGGR10_CSI2P:
>  	case libcamera::formats::SGBRG10_CSI2P:
>  	case libcamera::formats::SGRBG10_CSI2P:
> @@ -633,8 +666,8 @@ void ViewFinderGL::doRender()
>  	case libcamera::formats::SGRBG12_CSI2P:
>  	case libcamera::formats::SRGGB12_CSI2P:
>  		/*
> -		 * Packed raw Bayer 10-bit and 12-bit formats are stored in
> -		 * GL_RED texture.
> +		 * Raw Bayer 8-bit, and packed raw Bayer 10-bit/12-bit formats
> +		 * are stored in GL_RED texture.
>  		 */
>  		glActiveTexture(GL_TEXTURE0);
>  		configureTexture(*textures_[0]);