Integer scaling (IS) is a nearest-neighbor upscaling technique that simply scales up the existing pixels by an integer (i.e., whole number) multiplier. Nearest-neighbor (NN) interpolation works by filling in the missing color values in the upscaled image with that of the coordinate-mapped nearest source pixel value.
Both IS and NN preserve the clarity of the original image. In contrast, traditional upscaling algorithms, such as bilinear or bicubic interpolation, result in blurry upscaled images because they employ interpolation techniques that smooth out the transition from one pixel to another. Therefore, integer scaling is particularly useful for pixel art games that rely on sharp, blocky images to deliver their distinctive look.
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 - - Introduces new scaling filter property to allow userspace to select the driver's default scaling filter or Nearest-neighbor(NN) filter for scaling operations on crtc/plane. - Implements and enable integer scaling for i915
Userspace patch series link: TBD.
Thanks to Shashank for initiating this work. His initial RFC can be found here [1]
[1] https://patchwork.freedesktop.org/patch/337082/
Modifications done in this series - - refactored code and incorporated initial review comments and added 2 scaling filter types (default and NN) to begin with. - added scaling filter property support for planes and new API helpers for drivers to setup this property. - rewrote code to enable integer scaling and NN filter for i915
Pankaj Bharadiya (5): drm: Introduce scaling filter property drm/drm-kms.rst: Add Scaling filter property documentation drm/i915: Enable scaling filter for plane and pipe drm/i915: Introduce scaling filter related registers and bit fields. drm/i915/display: Add Nearest-neighbor based integer scaling support
Documentation/gpu/drm-kms.rst | 6 ++ drivers/gpu/drm/drm_atomic_uapi.c | 8 ++ drivers/gpu/drm/drm_crtc.c | 16 +++ drivers/gpu/drm/drm_mode_config.c | 13 +++ drivers/gpu/drm/drm_plane.c | 35 +++++++ drivers/gpu/drm/i915/display/intel_display.c | 100 ++++++++++++++++++- drivers/gpu/drm/i915/display/intel_display.h | 2 + drivers/gpu/drm/i915/display/intel_sprite.c | 32 ++++-- drivers/gpu/drm/i915/i915_reg.h | 21 ++++ include/drm/drm_crtc.h | 10 ++ include/drm/drm_mode_config.h | 6 ++ include/drm/drm_plane.h | 14 +++ 12 files changed, 252 insertions(+), 11 deletions(-)