Improve quality of GDI image scaling #18495
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Some example images demonstrating the difference between the original mode (on the left) and the new mode (on the right).
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I should mention there is also a |
DHowett
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Feb 3, 2025
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This looks perfect to me. Thanks!
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/azp run so tired of this new policy already |
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/azp run |
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Azure Pipelines successfully started running 1 pipeline(s). |
DHowett
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Apr 29, 2025
When Sixel images are rendered, they're automatically scaled to match the 10x20 cell size of the original hardware terminals. If this requires the image to be scaled down, the default GDI stretching mode can produce ugly visual artefacts, particularly for color images. This PR changes the stretching mode to `COLORONCOLOR`, which looks considerably better, but without impacting performance. The initial Sixel implementation was added in PR #17421. ## Validation Steps Performed I've tested with a number of different images using a small font size to trigger the downscaling, and I think the results are generally better, although simple black on white images are still better with the default mode (i.e. `BLACKONWHITE`), which is understandable. I've also checked the performance with a variation of the [sixel-bench] test, and confirmed that the new mode is no worse than the default. [sixel-bench]: https://github.com/jerch/sixel-bench (cherry picked from commit b243fb6) Service-Card-Id: PVTI_lADOAF3p4s4AmhmQzgZ0dHI Service-Version: 1.22
DHowett
pushed a commit
that referenced
this pull request
Apr 29, 2025
When Sixel images are rendered, they're automatically scaled to match the 10x20 cell size of the original hardware terminals. If this requires the image to be scaled down, the default GDI stretching mode can produce ugly visual artefacts, particularly for color images. This PR changes the stretching mode to `COLORONCOLOR`, which looks considerably better, but without impacting performance. The initial Sixel implementation was added in PR #17421. ## Validation Steps Performed I've tested with a number of different images using a small font size to trigger the downscaling, and I think the results are generally better, although simple black on white images are still better with the default mode (i.e. `BLACKONWHITE`), which is understandable. I've also checked the performance with a variation of the [sixel-bench] test, and confirmed that the new mode is no worse than the default. [sixel-bench]: https://github.com/jerch/sixel-bench (cherry picked from commit b243fb6) Service-Card-Id: PVTI_lADOAF3p4s4AxadtzgZ0dHA Service-Version: 1.23
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Summary of the Pull Request
When Sixel images are rendered, they're automatically scaled to match
the 10x20 cell size of the original hardware terminals. If this requires
the image to be scaled down, the default GDI stretching mode can produce
ugly visual artefacts, particularly for color images. This PR changes
the stretching mode to
COLORONCOLOR, which looks considerably better,but without impacting performance.
References and Relevant Issues
The initial Sixel implementation was added in PR #17421.
Validation Steps Performed
I've tested with a number of different images using a small font size to
trigger the downscaling, and I think the results are generally better,
although simple black on white images are still better with the default
mode (i.e.
BLACKONWHITE), which is understandable.I've also checked the performance with a variation of the sixel-bench
test, and confirmed that the new mode is no worse than the default.