https://bugs.kde.org/show_bug.cgi?id=414983
Bug ID: 414983
Summary: Motion Blur filter gives 512 x 512 tiling edge
artifacts
Product: krita
Version: 4.2.8
Platform: Debian stable
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Filters
Assignee: krita-bugs-n...@kde.org
Reporter: ahab.greybe...@hotmail.co.uk
Target Milestone: ---
SUMMARY
This was reported in the Krita Artists Forum:
https://krita-artists.org/t/motion-blur-bug/1720
This happens for krita version 4.2.6 onwards to the latest Dec 08 Windows
nightly portable .zip.
Here is an examples file (100MB .kra) made with the 4.2.8 appimage:
https://www.dropbox.com/s/wbfi3uton2q5byi/MBTilingOriginal.kra?dl=1
This contains two different 8-bit RGB images which have had the Motion Blur
filter applied. Also, it has an edge detected (Prewitt, All Sides, 1x1) image
to emphasise the artifacts.
I used manual application rather that a filter layer in case the filter layer
operations added any extra artifact effects.
An edge detected version of the original image is included to ensure that the
edge detection filter does not introduce artifacts, which it does not (but see
Additional Notes a:).
I tried it with the original images converted to 16-bit integer images and saw
no noticable differences in the artifacts. (See Additional Notes b:)
STEPS TO REPRODUCE
1. Apply a Motion Blur fliter to the image. If you adjust the Angle parameter
(using the rotation dial at first) around the zero degrees value +/- 20 degrees
you generally get line artifacts appearing. But they can appear all around the
dial.
2. Fine adjustment of Angle value can make them worse or better.
3. Length values of 4 or less seem to give no artifacts. Length values of 5 or
more do generally give artifacts but very large values of 30 or more do not, it
seems. (Only limited testing was done.)
4. Use of the edge detection filter helps to emphasise and also reveal faint
artifacts.
OBSERVED RESULT
See the attached .kra file
EXPECTED RESULT
There should be no artifacts
SOFTWARE/OS VERSIONS
Krita
Version: 4.2.8
Languages: en_GB, en
Hidpi: true
Qt
Version (compiled): 5.12.5
Version (loaded): 5.12.5
OS Information
Build ABI: x86_64-little_endian-lp64
Build CPU: x86_64
CPU: x86_64
Kernel Type: linux
Kernel Version: 4.19.0-6-amd64
Pretty Productname: Debian GNU/Linux 10 (buster)
Product Type: debian
Product Version: 10
OpenGL Info
Vendor: "NVIDIA Corporation"
Renderer: "GeForce GTX 750 Ti/PCIe/SSE2"
Version: "4.6.0 NVIDIA 418.74"
Shading language: "4.60 NVIDIA"
Requested format: QSurfaceFormat(version 3.0, options
QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24,
redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8,
stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer,
swapInterval 0, colorSpace QSurfaceFormat::DefaultColorSpace, profile
QSurfaceFormat::CompatibilityProfile)
Current format: QSurfaceFormat(version 4.6, options
QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24,
redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8,
stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer,
swapInterval 0, colorSpace QSurfaceFormat::DefaultColorSpace, profile
QSurfaceFormat::CompatibilityProfile)
Version: 4.6
Supports deprecated functions true
is OpenGL ES: false
QPA OpenGL Detection Info
supportsDesktopGL: true
supportsOpenGLES: true
isQtPreferOpenGLES: false
Hardware Information
GPU Acceleration: auto
Memory: 16039 Mb
Number of Cores: 8
Swap Location: /tmp
Current Settings
Current Swap Location: /tmp
Undo Enabled: 1
Undo Stack Limit: 18
Use OpenGL: 1
Use OpenGL Texture Buffer: 1
Use AMD Vectorization Workaround: 0
Canvas State: OPENGL_SUCCESS
Autosave Interval: 360
Use Backup Files: 1
Number of Backups Kept: 1
Backup File Suffix: ~
Backup Location: Same Folder as the File
Use Win8 Pointer Input: 0
Use RightMiddleTabletButton Workaround: 0
Levels of Detail Enabled: 0
Use Zip64: 0
ADDITIONAL INFORMATION
a: As used, with default values, the edge detection filter introduces no
artifacts. If you use Formula:Any, Output:some Edge option, Radius:Any then you
get horizontal artifacts at a 512 spacing, even on a plain colour image. This
may need to be the subject of a separate bug report.
b: With 16 bit images, the edge detection applied to the original images is
notably different from the result of applying it to 8-bit images. This is not
related to the purpose of this bug report and there may be a logical
explanation but it seems strange.
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