entransdnr

Operation

[translated from German transcode documentation]

The filter operates best on material in YUV/I420 format, but can also be used for RGB material.

It operates only on one image when no scene-change is recognized. This is determined by the proportion of pixels in an image that have exceeded all threshold values (so when this propertion exceeds the prescribed eEntransdnr:scene-change value).

The filter examines each pixel of a picture separately according to luma and chroma portions (YUV mode) and/or R/G/B portions (RGB mode), so that both brightness and color noise can be treated separately.

The threshold values luma-threshold and chroma-threshold indicate to what extent of difference between a pixel of the previous image and one of the current image a "cross fade" of pixels is applied. The former is used on the luma (or R) component, the latter on chroma (or G/B) components.

The threshold values luma-lock and chroma-lock indicate to what extent of difference between a pixel of the previous image and one of the current image a "replacement" by a previous pixel is performed, that is, whether the pixel value is kept locked. The former is used on the luma (or R) component, the latter on chroma (or G/B) components. In any event, a pixel will be "refreshed" after at most 30 locks.

In principle the threshold values should be larger than the lock values, so that a balanced relationship between "locking" and "cross-fading" ensues. The threshold values are compared with the differences (biased) of pixels, i.e. larger threshold values strengthen the filter effect, because also larger differences (differences) are thus filtered. The default parameter values should yield a usable result in most cases. The filter has (then) altogether beside that noise reduction a soft-drawing effect however without "streak-effect" with movement. After filtering noise-afflicted material, (e.g. MPEG) compression can save up to 25% bitrate (this can however clearly be more or less depending on material).

History

• transcode dnr filter [Gerhard Monzel]
• Also available in avidemux (Denoise)