From 8fe5bf1295799a63aca7a16469771e257e5cfc49 Mon Sep 17 00:00:00 2001
From: Brian Woods
Date: Wed, 22 Feb 2023 01:09:37 -0500
Subject: Add webp scripts and makefiles

Add scripts for testing compression quality and converting collections
of pngs to webps.
---
 webp/lossless_z_gen_graph.m | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100755 webp/lossless_z_gen_graph.m

(limited to 'webp/lossless_z_gen_graph.m')

diff --git a/webp/lossless_z_gen_graph.m b/webp/lossless_z_gen_graph.m
new file mode 100755
index 0000000..d363c49
--- /dev/null
+++ b/webp/lossless_z_gen_graph.m
@@ -0,0 +1,36 @@
+#!/usr/bin/octave
+% SPDX-FileCopyrightText: 2023 Brian Woods
+% SPDX-License-Identifier: GPL-2.0-or-later
+
+files = {'lossless_z_images/PNG_01-z_VAR.webp', ...
+         'lossless_z_images/PNG_02-z_VAR.webp', ...
+         'lossless_z_images/PNG_03-z_VAR.webp', ...
+         'lossless_z_images/PNG_04-z_VAR.webp'};
+var_values = 0:1:9;
+files_len = length(files);
+var_values_len = length(var_values);
+results = zeros(files_len, var_values_len);
+
+for i = 1:files_len
+	for j = 1:var_values_len;
+		filepath = strrep(files{i}, 'VAR', num2str(var_values(j), "%d"));
+		[file, ~,  ~] = stat(filepath);
+		results(i,j) = file.size;
+	end
+end
+
+% normalize
+for i = 1:files_len
+	results(i,:) = results(i,:)/max(results(i,:));
+end
+
+f = figure('visible','off');
+plot(var_values, results(1,:),"b-");
+hold on;
+plot(var_values, results(2,:), "g-");
+plot(var_values, results(3,:), "r-");
+plot(var_values, results(4,:), "c-");
+xlabel ("z compression level");
+ylabel ("normalized file size");
+legend ("PNG 01", "PNG 02", "PNG 03", "PNG 04");
+print('lossless_z_graph.png');
-- 
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