[Piglit] [PATCH] Add test to verify srgb conformance
sroland at vmware.com
sroland at vmware.com
Wed Jul 31 15:27:07 PDT 2013
From: Roland Scheidegger <sroland at vmware.com>
Tests accuracy of srgb->linear and linear->srgb conversion,
according to d3d10 rules as I understand them:
1) srgb->linear is permitted a tolerance of 0.5 on the srgb side
(meaning the result converted back to srgb (but before float->int
conversion) using perfect formula must not deviate more than 0.5)
2) linear->srgb is permitted a tolerance of 0.6 compared to using
perfect formula
3) additionally all srgb values must stay the same when doing
srgb to linear and then linear to srgb conversion.
This test does not actually verify 2) (which would need exhaustive
test of all float values) so if some floats outside these generated
by srgb->linear conversion get mapped to arbitrary values that will
go unnoticed. Likewise, correct behavior for floats outside 0.0-1.0
is not verified (including INFs and NaNs - the former should get clamped
to 0/255 in the end, NaNs should also get mapped to 0).
---
tests/general/CMakeLists.gl.txt | 1 +
tests/general/srgb_conformance.c | 238 ++++++++++++++++++++++++++++++++++++++
2 files changed, 239 insertions(+)
create mode 100644 tests/general/srgb_conformance.c
diff --git a/tests/general/CMakeLists.gl.txt b/tests/general/CMakeLists.gl.txt
index 1933b13..601dafc 100644
--- a/tests/general/CMakeLists.gl.txt
+++ b/tests/general/CMakeLists.gl.txt
@@ -145,5 +145,6 @@ piglit_add_executable (quad-invariance quad-invariance.c)
piglit_add_executable (clear-accum clear-accum.c)
piglit_add_executable (vs-point_size-zero vs-point_size-zero.c)
piglit_add_executable (triangle-guardband-viewport triangle-guardband-viewport.c)
+piglit_add_executable (srgb_conformance srgb_conformance.c)
# vim: ft=cmake:
diff --git a/tests/general/srgb_conformance.c b/tests/general/srgb_conformance.c
new file mode 100644
index 0000000..dbf224e
--- /dev/null
+++ b/tests/general/srgb_conformance.c
@@ -0,0 +1,238 @@
+/*
+ * Copyright © 2013 VMware, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ * Roland Scheidegger <sroland at vmware.com>
+ *
+ * Tests accuracy of srgb->linear and linear->srgb conversion,
+ * according to d3d10 rules:
+ * 1) srgb->linear is permitted a tolerance of 0.5 on the srgb side
+ * (meaning the result converted back to srgb (but before float->int
+ * conversion) using perfect formula must not deviate more than 0.5)
+ * 2) linear->srgb is permitted a tolerance of 0.6 compared to using
+ * perfect formula
+ * 3) additionally all srgb values must stay the same when doing
+ * srgb to linear and then linear to srgb conversion.
+ * This test does not actually verify 2) (which would need exhaustive
+ * test of all float values) so if some floats outside these generated
+ * by srgb->linear conversion get mapped to arbitrary values that will
+ * go unnoticed. Likewise, correct behavior for floats outside 0.0-1.0
+ * is not verified (including INFs and NaNs - the former should get clamped
+ * to 0/255 in the end, NaNs should also get mapped to 0).
+ *
+ */
+
+#include "piglit-util-gl-common.h"
+
+PIGLIT_GL_TEST_CONFIG_BEGIN
+
+ config.supports_gl_compat_version = 10;
+
+ config.window_width = 16;
+ config.window_height = 16;
+ config.window_visual = PIGLIT_GL_VISUAL_RGBA | PIGLIT_GL_VISUAL_DOUBLE;
+
+PIGLIT_GL_TEST_CONFIG_END
+
+
+static GLfloat
+linear_to_nonlinear(float x)
+{
+ if (x >= 1.0f)
+ return 255.0f;
+ else if (x >= 0.0031308f)
+ return 255.0f * (1.055f * powf(x, 0.41666f) - 0.055f);
+ else if (x > 0.0f)
+ return 255.0f * (12.92f * x);
+ else
+ return 0.0f;
+}
+
+static enum piglit_result test_format(void)
+{
+ GLboolean pass = GL_TRUE;
+ GLuint texsrgb, texfb, fb;
+ GLenum status;
+ int i;
+ float tex_vals[256][4];
+ float readf[256][4];
+ float tolerance;
+ GLubyte readb[256][4];
+ float maxErr = 0.0f;
+
+ for (i = 0; i < 256; i++) {
+ tex_vals[i][0] = (float)i / 255.0f;
+ tex_vals[i][1] = tex_vals[i][2] = 0.0f;
+ tex_vals[i][3] = 1.0f;
+ }
+
+ /* initialize texture */
+ glGenTextures(1, &texsrgb);
+ glBindTexture(GL_TEXTURE_2D, texsrgb);
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_SRGB8_ALPHA8_EXT,
+ 16, 16, 0,
+ GL_RGBA, GL_FLOAT, &tex_vals[0][0]);
+
+ glGenFramebuffersEXT(1, &fb);
+ glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fb);
+ glViewport(0, 0, piglit_width, piglit_height);
+
+ /* draw into float framebuffer and verify results */
+ glGenTextures(1, &texfb);
+ glBindTexture(GL_TEXTURE_2D, texfb);
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F_ARB,
+ piglit_width, piglit_height, 0,
+ GL_RGBA, GL_FLOAT, NULL);
+
+ glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT,
+ GL_COLOR_ATTACHMENT0_EXT,
+ GL_TEXTURE_2D,
+ texfb,
+ 0);
+ assert(glGetError() == 0);
+
+ status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
+ printf("Testing using fb float format");
+ if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
+ printf(" - fbo incomplete (status = %s)\n",
+ piglit_get_gl_enum_name(status));
+ piglit_report_subtest_result(PIGLIT_SKIP, "float fb");
+ return PIGLIT_SKIP;
+ }
+ printf("\n");
+
+ glColor4f(1, 1, 1, 1);
+ glEnable(GL_TEXTURE_2D);
+ glBindTexture(GL_TEXTURE_2D, texsrgb);
+
+ glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
+ glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_REPLACE);
+ glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
+
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+ piglit_draw_rect_tex(-1, -1, 2, 2,
+ 0, 0, 1, 1);
+
+ glDisable(GL_TEXTURE_2D);
+
+ /* have to make up our own error measuring, since we
+ measure error on srgb side (so with values mapped back to srgb
+ using accurate formula) */
+
+ tolerance = 0.5f; /* as required by d3d10 */
+ glReadPixels(0, 0, 16, 16, GL_RGBA, GL_FLOAT, &readf[0][0]);
+
+ for (i = 0; i < 256; i++) {
+// printf("readback: %f observed: %f expected: %f\n", readf[i][0],
+// linear_to_nonlinear(readf[i][0]), (float)i);
+ float err = fabs(linear_to_nonlinear(readf[i][0]) - (float)i);
+ if (err > maxErr) {
+ maxErr = err;
+ }
+ if (err > tolerance) {
+ printf(" failed when testing srgb->float result\n");
+ pass = GL_FALSE;
+ break;
+ }
+ }
+ printf("max error srgb->linear was %f\n", maxErr);
+
+ piglit_present_results();
+
+ piglit_report_subtest_result(pass ? PIGLIT_PASS : PIGLIT_FAIL,
+ "srgb->linear");
+
+ /* draw into srgb framebuffer and verify results */
+ glBindTexture(GL_TEXTURE_2D, texfb);
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_SRGB8_ALPHA8_EXT,
+ piglit_width, piglit_height, 0,
+ GL_RGBA, GL_FLOAT, NULL);
+
+ glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT,
+ GL_COLOR_ATTACHMENT0_EXT,
+ GL_TEXTURE_2D,
+ texfb,
+ 0);
+
+ assert(glGetError() == 0);
+
+ glEnable(GL_FRAMEBUFFER_SRGB_EXT);
+ status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
+ printf("Testing using fb srgb format");
+ if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
+ printf(" - fbo incomplete (status = %s)\n",
+ piglit_get_gl_enum_name(status));
+ piglit_report_subtest_result(PIGLIT_SKIP, "srgb fb");
+ return PIGLIT_SKIP;
+ }
+ printf("\n");
+
+ glEnable(GL_TEXTURE_2D);
+ glBindTexture(GL_TEXTURE_2D, texsrgb);
+ piglit_draw_rect_tex(-1, -1, 2, 2,
+ 0, 0, 1, 1);
+ glDisable(GL_TEXTURE_2D);
+
+ tolerance = 0.6f; /* as required by d3d10 */
+ /* TODO: should test this tolerance too really right now only test
+ the previously converted from srgb values, so we only enforce
+ any value stays the same when doing srgb->linear->srgb, which
+ corresponds to 0.5 tolerance but only for these exact values. */
+ glReadPixels(0, 0, 16, 16, GL_RGBA, GL_UNSIGNED_BYTE, &readb[0][0]);
+
+ for (i = 0; i < 256; i++) {
+// printf("observed: %d expected: %d\n", readb[i][0], i);
+ if (readb[i][0] != i) {
+ printf(" when testing srgb->float->srgb result\n");
+ pass = GL_FALSE;
+ break;
+ }
+ }
+
+ piglit_present_results();
+
+ piglit_report_subtest_result(pass ? PIGLIT_PASS : PIGLIT_FAIL,
+ "srgb->linear->srgb");
+
+ glDeleteTextures(1, &texfb);
+ glDeleteTextures(1, &texsrgb);
+ glDeleteFramebuffersEXT(1, &fb);
+
+ return pass ? PIGLIT_PASS : PIGLIT_FAIL;
+}
+
+enum piglit_result piglit_display(void)
+{
+ return test_format();
+}
+
+void piglit_init(int argc, char **argv)
+{
+ piglit_require_extension("GL_EXT_framebuffer_object");
+ piglit_require_extension("GL_ARB_texture_env_combine");
+ piglit_require_extension("GL_EXT_texture_sRGB");
+ piglit_require_extension("GL_ARB_framebuffer_sRGB");
+ piglit_require_extension("GL_ARB_color_buffer_float");
+ glDisable(GL_DITHER);
+}
--
1.7.9.5
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