Really bad color fringing in PDF on Linux from subpixel rendering |
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Issue descriptionChrome Version: 60.0.3112.101 (Official Build) (64-bit) OS: Linux What steps will reproduce the problem? (1) Scroll to page 56 of this PDF: http://arminda.whitman.edu/cgi/viewcontent.cgi?article=1384&context=theses What is the expected result? The rendering should be pleasing to the eye, and appear monochrome (it's a series of black-and-white equations). What happens instead? There is horrible color fringing, apparently from poorly-implemented subpixel anti-aliasing. I see cyan, yellow, and magenta. For graphics-related bugs, please copy/paste the contents of the about:gpu page at the end of this report. Graphics Feature Status Canvas: Hardware accelerated CheckerImaging: Disabled Flash: Hardware accelerated Flash Stage3D: Hardware accelerated Flash Stage3D Baseline profile: Hardware accelerated Compositing: Hardware accelerated Multiple Raster Threads: Enabled Native GpuMemoryBuffers: Software only. Hardware acceleration disabled Rasterization: Software only. Hardware acceleration disabled Video Decode: Software only, hardware acceleration unavailable Video Encode: Software only, hardware acceleration unavailable WebGL: Hardware accelerated WebGL2: Hardware accelerated Driver Bug Workarounds clear_uniforms_before_first_program_use disable_discard_framebuffer disable_framebuffer_cmaa force_cube_complete init_gl_position_in_vertex_shader init_vertex_attributes pack_parameters_workaround_with_pack_buffer scalarize_vec_and_mat_constructor_args unpack_alignment_workaround_with_unpack_buffer unpack_overlapping_rows_separately_unpack_buffer use_virtualized_gl_contexts Problems Detected Accelerated video decode is unavailable on Linux: 137247 Disabled Features: accelerated_video_decode Accelerated video encode is unavailable on Linux Disabled Features: accelerated_video_encode Program link fails in NVIDIA Linux if gl_Position is not set: 286468 Applied Workarounds: init_gl_position_in_vertex_shader Clear uniforms before first program use on all platforms: 124764, 349137 Applied Workarounds: clear_uniforms_before_first_program_use Linux NVIDIA drivers don't have the correct defaults for vertex attributes: 351528 Applied Workarounds: init_vertex_attributes Always rewrite vec/mat constructors to be consistent: 398694 Applied Workarounds: scalarize_vec_and_mat_constructor_args MakeCurrent is slow on Linux with NVIDIA drivers: 449150, 514510 Applied Workarounds: use_virtualized_gl_contexts NVIDIA fails glReadPixels from incomplete cube map texture: 518889 Applied Workarounds: force_cube_complete Pack parameters work incorrectly with pack buffer bound: 563714 Applied Workarounds: pack_parameters_workaround_with_pack_buffer Alignment works incorrectly with unpack buffer bound: 563714 Applied Workarounds: unpack_alignment_workaround_with_unpack_buffer Framebuffer discarding can hurt performance on non-tilers: 570897 Applied Workarounds: disable_discard_framebuffer Unpacking overlapping rows from unpack buffers is unstable on NVIDIA GL driver: 596774 Applied Workarounds: unpack_overlapping_rows_separately_unpack_buffer Limited enabling of Chromium GL_INTEL_framebuffer_CMAA: 535198 Applied Workarounds: disable_framebuffer_cmaa Disable KHR_blend_equation_advanced until cc shaders are updated: 661715 Accelerated rasterization has been disabled, either via blacklist, about:flags or the command line. Disabled Features: rasterization Native GpuMemoryBuffers have been disabled, either via about:flags or command line. Disabled Features: native_gpu_memory_buffers Checker-imaging has been disabled via finch trial or the command line. Disabled Features: checker_imaging Version Information Data exported 8/18/2017, 3:08:42 PM Chrome version Chrome/60.0.3112.101 Operating system Linux 4.4.0-83-generic Software rendering list version 13.8 Driver bug list version 10.93 ANGLE commit id 3e6a61fecba9 2D graphics backend Skia/60 d1f2d15b36f6a6a9d199581b998a7ca924a1f1a8- Command Line /usr/bin/google-chrome-stable --flag-switches-begin --flag-switches-end Driver Information Initialization time 345 In-process GPU false Passthrough Command Decoder false Supports overlays false Sandboxed true GPU0 VENDOR = 0x10de, DEVICE= 0x13ba Optimus false Optimus false AMD switchable false Driver vendor Nvidia Driver version 367.57 Driver date Pixel shader version 4.50 Vertex shader version 4.50 Max. MSAA samples 64 Machine model name Machine model version GL_VENDOR NVIDIA Corporation GL_RENDERER Quadro K2200/PCIe/SSE2 GL_VERSION 4.5.0 NVIDIA 367.57 GL_EXTENSIONS GL_AMD_multi_draw_indirect GL_AMD_seamless_cubemap_per_texture GL_ARB_arrays_of_arrays GL_ARB_base_instance GL_ARB_bindless_texture GL_ARB_blend_func_extended GL_ARB_buffer_storage GL_ARB_cl_event GL_ARB_clear_buffer_object GL_ARB_clear_texture GL_ARB_clip_control GL_ARB_color_buffer_float GL_ARB_compressed_texture_pixel_storage GL_ARB_conservative_depth GL_ARB_compute_shader GL_ARB_compute_variable_group_size GL_ARB_conditional_render_inverted GL_ARB_copy_buffer GL_ARB_copy_image GL_ARB_cull_distance GL_ARB_debug_output GL_ARB_depth_buffer_float GL_ARB_depth_clamp GL_ARB_depth_texture GL_ARB_derivative_control GL_ARB_direct_state_access GL_ARB_draw_buffers GL_ARB_draw_buffers_blend GL_ARB_draw_indirect GL_ARB_draw_elements_base_vertex GL_ARB_draw_instanced GL_ARB_enhanced_layouts GL_ARB_ES2_compatibility 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GL_EXT_multi_draw_arrays GL_EXT_packed_depth_stencil GL_EXT_packed_float GL_EXT_packed_pixels GL_EXT_pixel_buffer_object GL_EXT_point_parameters GL_EXT_polygon_offset_clamp GL_EXT_provoking_vertex GL_EXT_rescale_normal GL_EXT_secondary_color GL_EXT_separate_shader_objects GL_EXT_separate_specular_color GL_EXT_shader_image_load_formatted GL_EXT_shader_image_load_store GL_EXT_shader_integer_mix GL_EXT_shadow_funcs GL_EXT_stencil_two_side GL_EXT_stencil_wrap GL_EXT_texture3D GL_EXT_texture_array GL_EXT_texture_buffer_object GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_latc GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc GL_EXT_texture_cube_map GL_EXT_texture_edge_clamp GL_EXT_texture_env_combine GL_EXT_texture_env_dot3 GL_EXT_texture_filter_anisotropic GL_EXT_texture_integer GL_EXT_texture_lod GL_EXT_texture_lod_bias GL_EXT_texture_mirror_clamp GL_EXT_texture_object GL_EXT_texture_shared_exponent GL_EXT_texture_sRGB GL_EXT_texture_sRGB_decode 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GL_NV_fragment_program_option GL_NV_fragment_program2 GL_NV_framebuffer_multisample_coverage GL_NV_geometry_shader4 GL_NV_gpu_program4 GL_NV_internalformat_sample_query GL_NV_gpu_program4_1 GL_NV_gpu_program5 GL_NV_gpu_program5_mem_extended GL_NV_gpu_program_fp64 GL_NV_gpu_shader5 GL_NV_half_float GL_NV_light_max_exponent GL_NV_multisample_coverage GL_NV_multisample_filter_hint GL_NV_occlusion_query GL_NV_packed_depth_stencil GL_NV_parameter_buffer_object GL_NV_parameter_buffer_object2 GL_NV_path_rendering GL_NV_pixel_data_range GL_NV_point_sprite GL_NV_primitive_restart GL_NV_register_combiners GL_NV_register_combiners2 GL_NV_shader_atomic_counters GL_NV_shader_atomic_float GL_NV_shader_atomic_int64 GL_NV_shader_buffer_load GL_NV_shader_storage_buffer_object GL_NV_texgen_reflection GL_NV_texture_barrier GL_NV_texture_compression_vtc GL_NV_texture_env_combine4 GL_NV_texture_multisample GL_NV_texture_rectangle GL_NV_texture_shader GL_NV_texture_shader2 GL_NV_texture_shader3 GL_NV_transform_feedback GL_NV_transform_feedback2 GL_NV_uniform_buffer_unified_memory GL_NV_vdpau_interop GL_NV_vertex_array_range GL_NV_vertex_array_range2 GL_NV_vertex_attrib_integer_64bit GL_NV_vertex_buffer_unified_memory GL_NV_vertex_program GL_NV_vertex_program1_1 GL_NV_vertex_program2 GL_NV_vertex_program2_option GL_NV_vertex_program3 GL_NVX_conditional_render GL_NVX_gpu_memory_info GL_NVX_nvenc_interop GL_NV_shader_thread_group GL_NV_shader_thread_shuffle GL_SGIS_generate_mipmap GL_SGIS_texture_lod GL_SGIX_depth_texture GL_SGIX_shadow GL_SUN_slice_accum Disabled Extensions GL_KHR_blend_equation_advanced GL_KHR_blend_equation_advanced_coherent Window system binding vendor NVIDIA Corporation Window system binding version 1.4 Window system binding extensions GLX_EXT_visual_info GLX_EXT_visual_rating GLX_SGIX_fbconfig GLX_SGIX_pbuffer GLX_SGI_video_sync GLX_SGI_swap_control GLX_EXT_swap_control GLX_EXT_swap_control_tear GLX_EXT_texture_from_pixmap GLX_EXT_buffer_age GLX_ARB_create_context GLX_ARB_create_context_profile GLX_EXT_create_context_es_profile GLX_EXT_create_context_es2_profile GLX_ARB_create_context_robustness GLX_NV_delay_before_swap GLX_EXT_stereo_tree GLX_EXT_libglvnd GLX_ARB_context_flush_control GLX_NV_robustness_video_memory_purge GLX_ARB_multisample GLX_NV_float_buffer GLX_ARB_fbconfig_float GLX_NV_swap_group GLX_EXT_framebuffer_sRGB GLX_NV_copy_image GLX_NV_copy_buffer GLX_NV_video_capture Window manager Mutter (Muffin) XDG_CURRENT_DESKTOP X-Cinnamon GDMSESSION cinnamon Compositing manager Yes Direct rendering Yes Reset notification strategy 0x8252 GPU process crash count 0 System visual ID 33 RGBA visual ID 162 Compositor Information Tile Update Mode One-copy Partial Raster Enabled GpuMemoryBuffers Status ATC Software only ATCIA Software only DXT1 Software only DXT5 Software only ETC1 Software only R_8 Software only RG_88 Software only BGR_565 Software only RGBA_4444 Software only RGBX_8888 Software only RGBA_8888 Software only BGRX_8888 Software only BGRA_8888 Software only RGBA_F16 Software only YVU_420 Software only YUV_420_BIPLANAR Software only UYVY_422 Software only Log Messages [185355:185470:0818/135017.318126:WARNING:x11_util.cc(1364)] : X error received: serial 2737, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/135017.318231:WARNING:x11_util.cc(1364)] : X error received: serial 2739, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/135059.221966:WARNING:x11_util.cc(1364)] : X error received: serial 2846, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/143331.670486:WARNING:x11_util.cc(1364)] : X error received: serial 21385, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/143556.774810:WARNING:x11_util.cc(1364)] : X error received: serial 23207, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/144156.584095:WARNING:x11_util.cc(1364)] : X error received: serial 32006, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/144156.584170:WARNING:x11_util.cc(1364)] : X error received: serial 32008, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/144901.327253:WARNING:x11_util.cc(1364)] : X error received: serial 52401, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/144907.195078:WARNING:x11_util.cc(1364)] : X error received: serial 53289, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/145021.114132:WARNING:x11_util.cc(1364)] : X error received: serial 59337, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/145233.779130:WARNING:x11_util.cc(1364)] : X error received: serial 70512, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/145416.812787:WARNING:x11_util.cc(1364)] : X error received: serial 77352, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/145417.496523:WARNING:x11_util.cc(1364)] : X error received: serial 77439, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown) [185355:185470:0818/150447.537973:WARNING:x11_util.cc(1364)] : X error received: serial 123024, error_code 3 (BadWindow), request_code 4, minor_code 0 (Unknown)
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Aug 18 2017
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Aug 21 2017
Tested the issue on Ubuntu 14.04 and Mac os 10.12.6 using chrome M60 #60.0.3112.101 and M62 #62.0.3192.0 and issue is not observed in scrolling the pdf. Attached screencast and GPU details for reference. @rlanday-- Could you please let us know the OS details in which you are facing the issue and also please check attached screencast and confirm us if we have missed any steps in reproducing the issue. Thanks!
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Aug 24 2017
(Wrong PDF component)
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Aug 24 2017
This is on my Google workstation: rlanday@rlanday0:~$ uname -a Linux <hostname> 4.4.0-83-generic #106~14.04.1-Ubuntu SMP Mon Jun 26 18:10:19 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
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Aug 24 2017
Color fringing is visible at 0:52 in the video.
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Aug 24 2017
Looks like I forgot to put the screenshot up:
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Aug 24 2017
I see it on my laptop too, but only at certain zoom levels. BTW, it's actually the 62nd page in the PDF, which is labelled 56 at the bottom.
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Aug 24 2017
bungeman: Got any advice on this one? I went back to Chrome 55 and it's got the same issue, so it's not a regression from the bundled FreeType.
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Aug 24 2017
I can't remember off hand if these are glyphs being drawn by Skia or directly by PDFium. When PDFium draws subpixel anti-aliased glyphs itself it does tend to have quite bad color fringing (which will be especially prominent on long vertical lines like these). Even worse, if one selects and deselects these glyphs then the rendering changes (the aren't drawn the same after the selection is de-selected).
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Aug 24 2017
Can you determine what LCD filter (default, light, legacy, none, or specific weights) was applied, if any? This is the most important step in reducing color fringes. Gamma correction also contributes, but much less critically.
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Aug 24 2017
Skia isn't enabled in PDFium, yet. Text in PDFium is drawn directly by PDFium itself.
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Aug 28 2017
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Mar 5 2018
I think this is a bit better at this point, due to the removal of the odd contrast boost for glyphs from pdfium. It's still color fringy due to the lack of either filter or linear blending, but at least it's not being made worse. These vertical glyphs still look less than ideal, but at least they're not glowing anymore.
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Mar 5 2018
The change #14 refers to is https://pdfium-review.googlesource.com/c/pdfium/+/16992 Should we close this?
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Mar 5 2018
Well, it is still pretty bad. There were three issues involved (contrast boost, no filtering, no linear blending) and one of them has been fixed. I think longer term the idea is to fix the other two by moving to Skia for rendering, so this could probably be duped against that issue, if it exists.
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Mar 5 2018
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Mar 5 2018
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Jun 4 2018
Please file the bug report with FreeType if you can be sure that FreeType handles the bars and the rest of the text. It is a startling difference between the (unfiltered) bars and the rest of the (filtered) text. If you happen to use FT_Outline_Get_Bitmap or FT_Outline_Render, that would explain a lot because they are "unfiltered by design". Even if FreeType does not handle those bars, it should handle small custom features like this IMHO. FreeType should handle bars, slashes, lines, doublelines, underlines, strikethroughs, hexagons, and whatever else small lineart not in a font, so that chemical and mathematical formulas can be rendered using a single one consistent rendering algorithm. |
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Comment 1 by rlanday@chromium.org
, Aug 18 2017