Detecting and mitigating artifacts related to high chromatic colors

Patent metadata

Field	Value
Publication number	US-2023144311-A1
Application number	US-202117523762-A
Country	US
Kind code	A1
Filing date	Nov 10, 2021
Priority date	Nov 10, 2021
Publication date	May 11, 2023
Grant date	—

Abstract

Systems, apparatuses, and methods for detecting and mitigating scaling artifacts caused by high chromatic colors in adjacent pixels are disclosed. A blend factor calculation circuit determines if high chromatic colors are in close proximity to each other in a set of pixel data of an image or frame. The blend factor calculation circuit generates a blend factor value to suppress artifacts which are introduced when filtering the set of pixel data when the set of pixel data has high chromatic colors in close proximity. In one scenario, the blend factor calculation circuit calculates pixel component difference values of adjacent pixels and uses a value calculated based on the difference values as an input to a transfer function. The output of the transfer function is a blend factor value which determines how filtering is blended between a plurality of filters.

First claim

What is claimed is:

1 . An apparatus comprising:
a blend factor calculation circuit configured to:
access a set of input pixels; and
generate a blend factor value, in response to determining two adjacent pixels of the input pixels have perceived brightness values exceeding a first threshold and hue values that differ by at least a second threshold; and
a blend circuit configured to select one of a plurality of filters for processing the set of input pixels, based at least in part on the blend factor value.

2 . The apparatus as recited in claim 1 , wherein the blend factor calculation unit is further configured to:
generate a chroma fix value which is representative of a degree to which the set of pixel data includes two brightly lit adjacent pixels having significantly different hues; and generate the blend factor value based on the chroma fix value.

3 . The apparatus as recited in claim 2 , wherein the blend factor calculation unit is further configured to convert the chroma fix value with a transfer function so as to generate the blend factor value.

4 . The apparatus as recited in claim 1 , wherein the blend factor calculation unit is further configured to:
calculate pixel component difference values for a plurality of pixel components of adjacent pixels; and calculate a max-min difference between a maximum pixel component difference value and a minimum pixel component difference value.

5 . The apparatus as recited in claim 4 , wherein the blend factor calculation unit is further configured to:
calculate, for each separate pixel, a pixel component difference between a maximum pixel component value and a minimum pixel component value; and calculate a product of the max-min difference multiplied by a first pixel component difference of a first pixel multiplied by a second pixel component difference of a second pixel.

6 . The apparatus as recited in claim 5 , wherein the blend factor calculation circuit is further configured to:
convert the product with a transfer function to generate a first intermediate blend factor value; and generate the blend factor value based at least in part on the first intermediate blend factor value.

7 . The apparatus as recited in claim 6 , wherein the blend factor calculation circuit is further configured to:
determine if the first intermediate blend factor value is less than one or more other intermediate blend factor values; and set the blend factor value equal to the first intermediate blend factor value responsive to determining that the first intermediate blend factor value is less than one or more other intermediate blend factor values.

8 . A method comprising:
generating, by a blend factor calculation circuit, a chroma fix value which is representative of a degree to which a set of input pixels include two brightly lit adjacent pixels having significantly different hues; generating a blend factor value based on the chroma fix value; and selecting, by a blend circuit, one of a plurality of filters for processing the set of input pixels, based at least in part on the blend factor value, wherein subsequent to filtering, blended pixel data is driven to a display.

9 . The method as recited in claim 8 , wherein generating the chroma fix value comprises:
determining if a hue difference between a first pixel and a second pixel is greater than a first threshold, wherein the set of pixel data comprises the first pixel and the second pixel; determining if a luminance value of the first pixel value is greater than a second threshold; and determining if a luminance value of the second pixel value is greater than the second threshold.

10 . The method as recited in claim 9 , wherein the second threshold is greater than the first threshold.

11 . The method as recited in claim 8 , wherein generating the chroma fix value comprises:
calculating pixel component difference values for a plurality of pixel components of adjacent pixels; calculating a max-min difference between a maximum pixel component difference value and a minimum pixel component difference value; calculating, for each separate pixel, a pixel component difference between a maximum pixel component value and a minimum pixel component value; and calculating the chroma fix value as a product of the max-min difference multiplied by a first pixel component difference of a first pixel multiplied by a second pixel component difference of a second pixel.

12 . The method as recited in claim 11 , further comprising:
converting the chroma fix value with a transfer function to generate a first intermediate blend factor value; generating the blend factor value based at least in part on the first intermediate blend factor value; selecting a sharper narrow filter as the second filter responsive to the product being greater than or equal to zero; and selecting a blurrier narrow filter as the second filter responsive to the product being less than zero.

13 . The method as recited in claim 12 , further comprising:
determining if the first intermediate blend factor value is less than one or more other intermediate blend factor values; and setting the blend factor value equal to the first intermediate blend factor value responsive to determining that the first intermediate blend factor value is less than one or more other intermediate blend factor values.

14 . The method as recited in claim 12 , further comprising:
selecting a first piece-wise linear (PWL) function for generating the first intermediate blend factor value from the chroma fix value if an input image is in a first format; and selecting a second PWL function for generating the first intermediate blend factor value from the chroma fix value if the input image is in a second format, wherein the second PWL function is different from the first PWL function.

15 . A system comprising:
a memory storing a set of input pixels; and circuitry configured to:
generate a blend factor value, in response to determining two adjacent pixels of the input pixels have perceived brightness values exceeding a first threshold and hue values that differ by at least a second threshold; and
select one of a plurality of filters for processing the set of input pixels, based at least in part on the blend factor value.

16 . The system as recited in claim 15 , wherein the circuitry is further configured to:
generate a chroma fix value which is representative of a degree to which the set of pixel data includes two brightly lit adjacent pixels having significantly different hues; and generate the blend factor value based on the chroma fix value.

17 . The system as recited in claim 16 , wherein the circuitry is further configured to convert the chroma fix value with a transfer function so as to generate the blend factor value.

18 . The system as recited in claim 15 , wherein the circuitry is further configured to:
calculate pixel component difference values for a plurality of pixel components of adjacent pixels; and calculate a max-min difference between a maximum pixel component difference value and a minimum pixel component difference value.

19 . The system as recited in claim 18 , wherein the circuitry is further configured to:
calculate, for each separate pixel, a pixel component difference between a maximum pixel component value and a minimum pixel component value; and calculate a product of the max-min difference multiplied by a first pixel component difference of a first pixel multiplied by a second pixel component difference of a s

Assignees

• Ati Technologies Ulc

Inventors

• Lee Keith
• Lees Isobel

Classifications

• G06T5/92

  based on global image properties · CPC title

• G06T5/70 Primary

  Denoising; Smoothing · CPC title

• G06T2207/10024

  Color image · CPC title

• G06T5/20

  using local operators · CPC title

• G06T2207/20024

  Filtering details · CPC title