From patchwork Wed Apr 6 10:11:00 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 15626 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id 4D103C0F1B for ; Wed, 6 Apr 2022 10:11:10 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id 6C73365644; Wed, 6 Apr 2022 12:11:09 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=libcamera.org; s=mail; t=1649239869; bh=otSvnRmyVnhI5y0srgWByJOjR0FsDrD1cMlLsA6vZiw=; h=To:Date:Subject:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=vzN4FEOImQQT7a6vtH+ptGL+lYDK50hrB+LzkYQZEY0CDe33IJ6Gs59kQ8DLqvUbB 4XRxicsgbqAwNfZo6iYk15PDxRbzaxWu1vqmvynp9hNwKSpYr3rrdg+qgfEbkpRdBg rIDLJMmAGAg5I/8CMeurYWGL3opBbw6v9YBXJLLyQCOHiU87WDb4JapyBXOgVPzUAv g9arwSZ6U5OFOD3Bt4j0s9x4gwibwjVAr3/1Gi1bB+dhBtwoaszDLlmXBMd1Y5KdOJ zVnW43nQnSUw+yJZm44o110Muw6YA9C2l60VDxsq8W3sSTzwa/50VIgBWkcNjh/lpT QBluX62YvmxyA== Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 6E24C633A4 for ; Wed, 6 Apr 2022 12:11:08 +0200 (CEST) Authentication-Results: lancelot.ideasonboard.com; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="LrvoZbNs"; dkim-atps=neutral Received: from pendragon.home (117.145-247-81.adsl-dyn.isp.belgacom.be [81.247.145.117]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id ED99D482; Wed, 6 Apr 2022 12:11:07 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1649239868; bh=otSvnRmyVnhI5y0srgWByJOjR0FsDrD1cMlLsA6vZiw=; h=From:To:Cc:Subject:Date:From; b=LrvoZbNs33h2/RPRFERWZyGCdJR+r7CcLZ8XfvUBeMt469cmyHfHhpuk1Fi0DmdXP n7Ic0KH0QqWv9ENuIyHsKJRAaX/NMcmYRyehcjldOk5zRKLDw/Fd/5vqCtyJqZjAuT DCmdpnL9dPvWJSX4QmCSkB4kP+huL+IYL5kFzZaU= To: libcamera-devel@lists.libcamera.org Date: Wed, 6 Apr 2022 13:11:00 +0300 Message-Id: <20220406101100.23502-1-laurent.pinchart@ideasonboard.com> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Subject: [libcamera-devel] [PATCH v3] ipa: raspberrypi: alsc: Limit the calculated lambda values X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Laurent Pinchart via libcamera-devel From: Laurent Pinchart Reply-To: Laurent Pinchart Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" From: Naushir Patuck Under the right circumstances, the alsc calculations could spread the colour errors across the entire image as lambda remains unbound. This would cause the corrected image chroma values to slowly drift to incorrect values. This change adds a config parameter (alsc.lambda_bound) that provides an upper and lower bound to the lambda value at every stage of the calculation. With this change, we now adjust the lambda values so that the average across the entire grid is 1 instead of normalising to the minimum value. Signed-off-by: Naushir Patuck Reviewed-by: David Plowman Reviewed-by: Laurent Pinchart Signed-off-by: Laurent Pinchart Tested-by: Naushir Patuck --- Changes since v2: - Fix typo - Use Span and std::accumulate Naush, could you please test this to make sure I haven't messed up anything ? src/ipa/raspberrypi/controller/rpi/alsc.cpp | 58 +++++++++++++++------ src/ipa/raspberrypi/controller/rpi/alsc.hpp | 1 + 2 files changed, 44 insertions(+), 15 deletions(-) diff --git a/src/ipa/raspberrypi/controller/rpi/alsc.cpp b/src/ipa/raspberrypi/controller/rpi/alsc.cpp index be3d1ae476cd..e575c14a92db 100644 --- a/src/ipa/raspberrypi/controller/rpi/alsc.cpp +++ b/src/ipa/raspberrypi/controller/rpi/alsc.cpp @@ -4,9 +4,12 @@ * * alsc.cpp - ALSC (auto lens shading correction) control algorithm */ + #include +#include #include +#include #include "../awb_status.h" #include "alsc.hpp" @@ -149,6 +152,7 @@ void Alsc::Read(boost::property_tree::ptree const ¶ms) read_calibrations(config_.calibrations_Cb, params, "calibrations_Cb"); config_.default_ct = params.get("default_ct", 4500.0); config_.threshold = params.get("threshold", 1e-3); + config_.lambda_bound = params.get("lambda_bound", 0.05); } static double get_ct(Metadata *metadata, double default_ct); @@ -610,30 +614,47 @@ static double compute_lambda_top_end(int i, double const M[XY][4], // Gauss-Seidel iteration with over-relaxation. static double gauss_seidel2_SOR(double const M[XY][4], double omega, - double lambda[XY]) + double lambda[XY], double lambda_bound) { + const double min = 1 - lambda_bound, max = 1 + lambda_bound; double old_lambda[XY]; int i; for (i = 0; i < XY; i++) old_lambda[i] = lambda[i]; lambda[0] = compute_lambda_bottom_start(0, M, lambda); - for (i = 1; i < X; i++) + lambda[0] = std::clamp(lambda[0], min, max); + for (i = 1; i < X; i++) { lambda[i] = compute_lambda_bottom(i, M, lambda); - for (; i < XY - X; i++) + lambda[i] = std::clamp(lambda[i], min, max); + } + for (; i < XY - X; i++) { lambda[i] = compute_lambda_interior(i, M, lambda); - for (; i < XY - 1; i++) + lambda[i] = std::clamp(lambda[i], min, max); + } + for (; i < XY - 1; i++) { lambda[i] = compute_lambda_top(i, M, lambda); + lambda[i] = std::clamp(lambda[i], min, max); + } lambda[i] = compute_lambda_top_end(i, M, lambda); + lambda[i] = std::clamp(lambda[i], min, max); // Also solve the system from bottom to top, to help spread the updates // better. lambda[i] = compute_lambda_top_end(i, M, lambda); - for (i = XY - 2; i >= XY - X; i--) + lambda[i] = std::clamp(lambda[i], min, max); + for (i = XY - 2; i >= XY - X; i--) { lambda[i] = compute_lambda_top(i, M, lambda); - for (; i >= X; i--) + lambda[i] = std::clamp(lambda[i], min, max); + } + for (; i >= X; i--) { lambda[i] = compute_lambda_interior(i, M, lambda); - for (; i >= 1; i--) + lambda[i] = std::clamp(lambda[i], min, max); + } + for (; i >= 1; i--) { lambda[i] = compute_lambda_bottom(i, M, lambda); + lambda[i] = std::clamp(lambda[i], min, max); + } lambda[0] = compute_lambda_bottom_start(0, M, lambda); + lambda[0] = std::clamp(lambda[0], min, max); double max_diff = 0; for (i = 0; i < XY; i++) { lambda[i] = old_lambda[i] + (lambda[i] - old_lambda[i]) * omega; @@ -653,15 +674,24 @@ static void normalise(double *ptr, size_t n) ptr[i] /= minval; } +// Rescale the values so that the average value is 1. +static void reaverage(Span data) +{ + double sum = std::accumulate(data.begin(), data.end(), 0.0); + double ratio = 1 / (sum / data.size()); + for (double &d : data) + d *= ratio; +} + static void run_matrix_iterations(double const C[XY], double lambda[XY], double const W[XY][4], double omega, - int n_iter, double threshold) + int n_iter, double threshold, double lambda_bound) { double M[XY][4]; construct_M(C, W, M); double last_max_diff = std::numeric_limits::max(); for (int i = 0; i < n_iter; i++) { - double max_diff = fabs(gauss_seidel2_SOR(M, omega, lambda)); + double max_diff = fabs(gauss_seidel2_SOR(M, omega, lambda, lambda_bound)); if (max_diff < threshold) { LOG(RPiAlsc, Debug) << "Stop after " << i + 1 << " iterations"; @@ -675,10 +705,8 @@ static void run_matrix_iterations(double const C[XY], double lambda[XY], << last_max_diff << " to " << max_diff; last_max_diff = max_diff; } - // We're going to normalise the lambdas so the smallest is 1. Not sure - // this is really necessary as they get renormalised later, but I - // suppose it does stop these quantities from wandering off... - normalise(lambda, XY); + // We're going to normalise the lambdas so the total average is 1. + reaverage({ lambda, XY }); } static void add_luminance_rb(double result[XY], double const lambda[XY], @@ -737,9 +765,9 @@ void Alsc::doAlsc() compute_W(Cb, config_.sigma_Cb, Wb); // Run Gauss-Seidel iterations over the resulting matrix, for R and B. run_matrix_iterations(Cr, lambda_r_, Wr, config_.omega, config_.n_iter, - config_.threshold); + config_.threshold, config_.lambda_bound); run_matrix_iterations(Cb, lambda_b_, Wb, config_.omega, config_.n_iter, - config_.threshold); + config_.threshold, config_.lambda_bound); // Fold the calibrated gains into our final lambda values. (Note that on // the next run, we re-start with the lambda values that don't have the // calibration gains included.) diff --git a/src/ipa/raspberrypi/controller/rpi/alsc.hpp b/src/ipa/raspberrypi/controller/rpi/alsc.hpp index 9616b99ea7ca..d1dbe0d1d22d 100644 --- a/src/ipa/raspberrypi/controller/rpi/alsc.hpp +++ b/src/ipa/raspberrypi/controller/rpi/alsc.hpp @@ -41,6 +41,7 @@ struct AlscConfig { std::vector calibrations_Cb; double default_ct; // colour temperature if no metadata found double threshold; // iteration termination threshold + double lambda_bound; // upper/lower bound for lambda from a value of 1 }; class Alsc : public Algorithm