Blurry outputs during upscaling the video buffer, is a generic problem of graphics industry. One of the major reason behind this blurriness is the interpolation of pixel values used by most of the upscaling hardwares.
Nearest-neighbor is a scaling mode, which works by filling in the missing color values in the upscaled image with that of the coordinate-mapped nearest source pixel value.
Nearest-neighbor can produce (almost) non-blurry scaling outputs when the scaling ratio is complete integer. For example: - input buffer resolution: 1280x720(HD) - output buffer resolution: 3840x2160(UHD/4K) - scaling ratio (h) = 3840/1280 = 3 - scaling ratio (v) = 2160/720 = 3
In such scenarios, we should try to pick Nearest-neighbor as scaling method when possible.
Many gaming communities have been asking for integer-mode scaling support, some links and background: https://software.intel.com/en-us/articles/integer-scaling-support-on-intel-g... http://tanalin.com/en/articles/lossless-scaling/ https://community.amd.com/thread/209107 https://www.nvidia.com/en-us/geforce/forums/game-ready-drivers/13/1002/featu...
This patch series adds support for programmable scaling filters, which can help a user to pick and enables NN scaling on Intel display hardware (ICL onwards). There is also one option to pick NN only when the scaling ratios are integer, to achieve Integer scaling, without(alsmost) any side effets.
there was an RFC series published for the same, which can be seen here: https://patchwork.freedesktop.org/series/66175/
Shashank Sharma (3): drm: Introduce scaling filter mode property drm/i915: Add support for scaling filters drm/i915: Handle nearest-neighbor scaling filter
drivers/gpu/drm/drm_atomic_uapi.c | 4 + drivers/gpu/drm/i915/display/intel_display.c | 161 +++++++++++++++++- .../drm/i915/display/intel_display_types.h | 3 + drivers/gpu/drm/i915/i915_reg.h | 31 ++++ include/drm/drm_crtc.h | 26 +++ include/drm/drm_mode_config.h | 6 + 6 files changed, 230 insertions(+), 1 deletion(-)