Resized image compression based on frequency content

• US 9,020,291 B2
• Filed: 08/31/2012
• Issued: 04/28/2015
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: Snapfish, LLC (District Photo Incorporated)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Gaubatz, Matthew D., Chan, Aaron
• Primary Examiner(s): Liu, Li
• Application Number:
  US13/600,611
• Publication Number:
  US 20140064631A1
• Time in Patent Office: 970 Days
• Field of Search: None
• US Class Current: 382/251
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution

Abstract

Examples disclosed herein relate to compressing an image by resizing an image and compressing the resized image based on frequency content. A processor may resize an image to a target size if the pixel area of the image is greater than the sum of the target pixel area plus a resizing tolerance. The processor may compress the image using a first data removal rule for a portion of the image of a first frequency range and using a second data removal rule for a portion of the image of a second frequency range.

Claims

1. An apparatus, comprising:

a processor to;

resize an image to a target pixel area if the pixel area of the image is greater than the sum of the target pixel area plus a resizing tolerance between the initial pixel area of the image and the target pixel area; and

compress a first portion of the image using a first data removal rule for content of a first frequency range; and

compress a second portion of the image using a second data removal rule for a second frequency range.

2. The apparatus of claim 1, wherein the processor further determines the resizing tolerance as a percentage of the target size.

3. The apparatus of claim 1, wherein the first frequency range is lower than the second frequency range and where the first data removal rule comprises a uniform quantization compression scheme.

4. The apparatus of claim 1, wherein the first frequency range is lower than the second frequency range and where the second data removal rule comprises a non-uniform quantization compression scheme.

5. The apparatus of claim 1, wherein determining the first data removal rule and the second data removal rule is based on the data to be compressed.

6. The apparatus of claim 1, wherein the resizing tolerance is based on one of a target compressed file bit and a target compressed image quality.

7. The apparatus of claim 1, wherein the resizing tolerance is indicated by a user based on a desired quality level.

8. The apparatus of claim 1, wherein the processor further determines the resizing tolerance as a percentage of the original image size.

9. A method comprising:

comparing a pixel area of an image to target pixel area plus a resizing tolerance;

resizing the image to the target pixel area if the pixel area of the image is greater than the target pixel area plus the resizing tolerance;

compressing a first portion of the image associated with a first frequency range by removing data using a first rule; and

compressing a second portion of the image associated with a frequency range greater than that of the first portion by removing data using a second rule.

10. The method of claim 9, further comprising determining the resizing tolerance based on a particular a percentage of the target pixel area.

11. The method of claim 9, wherein the first rule comprises a uniform quantization rule and wherein the second rule comprises a non-uniform quantization rule.

12. The method of claim 9, wherein resizing the image to the target pixel area comprises:

determining a set of possible pixel area sizes of the image achievable through compressed image decoding;

selecting the smallest pixel area size in the set above the target pixel area plus the resizing tolerance; and

reducing the image to the selected pixel area size through compressed image decoding.

13. The method of claim 12, further comprising:

widening a central integer bin based on the first rule; and

modifying a non-central integer bin to adjust to the size of the central bin based on the second rule.

14. The method of claim 9, wherein the first rule selects a compression quantizer in a manner that maps a given range of numbers to different integer bins.

15. The method of claim 9, wherein the second rule selects a compression quantizer in a manner that maps a different range of numbers to different integer bins.

16. A machine-readable non-transitory storage medium comprising instructions executable by a processor to:

compare a pixel area of an image to a target pixel area plus a resizing tolerance between the pixel area of the image and the target pixel area;

alter the pixel area of the image to the target pixel area if the pixel area of the image is greater than the sum of a target pixel area plus the resizing tolerance;

apply a first compression rule to a first portion of the image with a first frequency range; and

apply a second compression rule to a second portion of the image with a second frequency range greater than the first frequency range.

17. The machine-readable non-transitory storage medium of claim 16, further comprising selecting the first rule based on an image coefficient value to be compressed by the first rule.

18. The machine-readable non-transitory storage medium of claim 16, wherein the first compression rule comprises a uniform quantization compression scheme and wherein the second compression rule comprises a non-uniform quantization compression scheme.

19. The machine-readable non-transitory storage medium of claim 16, wherein the image is a compressed image and further comprising instructions to:

determine possible decoded sizes of the image;

determine the smallest size of the decoded input image above the sum of the target pixel area plus a resizing tolerance;

resize the input image to a raw image of the smallest size above the sum of the target pixel area plus the resizing tolerance; and

resize the raw image from the smallest size above the sum of the target pixel area plus the resizing tolerance to the target pixel area if the pixel area of the image is greater than the sum of a target pixel area plus a resizing tolerance.