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Determining orientation of images containing blue sky

  • US 6,512,846 B1
  • Filed: 11/29/1999
  • Issued: 01/28/2003
  • Est. Priority Date: 11/29/1999
  • Status: Expired due to Term
First Claim
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1. A method of determining image orientation comprising:

  • classifying potential sky pixels in said image by color;

    identifying spatially contiguous regions of said potential sky pixels;

    identifying actual sky regions by eliminating ones of said spatially contiguous regions that have a texture above a predetermined texture threshold;

    computing desaturation gradients of said actual sky regions;

    classifying said image as one of portrait and landscape based on average absolute values of horizontal and vertical desaturation gradient of pixels within each of said actual sky regions;

    determining orientation of said image based on a polarity of said average horizontal and vertical desaturation gradients; and

    confirming that said actual sky regions are true sky regions by comparing said desaturation gradients with a predetermined desaturation gradient for sky.

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