Circuit apparatus, electronic instrument, and error detection method
A circuit apparatus includes an image acquisition circuit, an error detection circuit, and a search circuit. The error detection circuit determines an indicator representing the degree of dissimilarity between a foreground image and a background image out of a display image based on the result of correlation operation and performs error detection on the display image based on the indicator. The search circuit searches the display image for the display position of the foreground image based on the reference image, which serves as a reference for the foreground image. The error detection circuit performs the error detection based on the display position searched for by the search circuit.
1. A circuit apparatus comprising:
an image acquisition circuit configured to acquire a display image including a foreground image in a given area of the display image and a background image corresponding to a background of the foreground image out of the display image;
an error detection circuit configured to:
determine histograms of pixel values of the display image to perform a correlation operation using the histograms;
determine an indicator representing a degree of dissimilarity between the foreground image and the background image based on a result of the correlation operation; and
perform an error detection on the display image based on the indicator; and
a search circuit configured to:
divide the display image into a plurality of band-shaped areas and divide each of the plurality of band-shaped areas into a plurality of individual areas;
perform fast Fourier transform processing on each edge image of the plurality of individual areas of the display image to obtain a first two-dimensional fast Fourier transform result including a plurality of first spatial frequency components;
perform the fast Fourier transform processing on an edge image of a reference image of the foreground image to obtain a second two-dimensional fast Fourier transform result including a plurality of second spatial frequency components, wherein the plurality of first and second spatial frequency components have the same number of rows and columns; and
perform inverse fast Fourier transform processing on the first and second two-dimensional fast Fourier transform results, by comparing every component of the plurality of first spatial frequency components with every corresponding component of the plurality of second spatial frequency components, to obtain an inverse fast Fourier transform result, the inverse fast Fourier transform result corresponding to a first plurality of cross-correlations between every edge image of the plurality of individual areas of the display image and the edge image of the reference image of the foreground image,
wherein the error detection circuit is further configured to:
generate a second cross-correlation between the display image and the reference image based on the first plurality of cross-correlations;
determine whether the second cross-correlation contains a value that is equal to or more than a threshold value;
detect a foreground image position where the second cross-correlation contains the value that is equal to or more than the threshold value as a position of the foreground image in the display image;
set a target area in the display image based on the detected foreground image position, the target area being a rectangular area in which the detected foreground image position is a center thereof and the foreground image is contained; and
perform the error detection with respect to the target area of the display image based on the indicator.
2. The circuit apparatus according to claim 1 ,
wherein the error detection circuit is configured to perform the error detection when the foreground image position is detected, and
the error detection circuit does not perform the error detection when the foreground image position is not detected.
3. The circuit apparatus according to claim 2 ,
wherein the error detection circuit does not detect the foreground image position when the second cross-correlation contains the value that is less than the threshold value.
4. The circuit apparatus according to claim 1 ,
wherein the error detection circuit is further configured to:
determine a histogram of each of components that form a color space;
perform an autocorrelation operation on the histogram of each of the components to determine a distance at which an autocorrelation value peaks for each of the components; and
determine the indicator based on a largest distance out of the determined distances.
5. The circuit apparatus according to claim 1 ,
wherein the error detection circuit is further configured to:
determine a first histogram of each of components that form a color space from the display image and a second histogram of each of the components from the reference image;
perform a cross-correlation operation on the first histogram and the second histogram for each of the components; and
determine the indicator based on a peak value of a peak provided by the cross-correlation.
6. The circuit apparatus according to claim 1 ,
wherein the error detection circuit is further configured to:
determine a second indicator representing a degree of agreement between the foreground image and the reference image based on the pixel values of the display image and pixel values of the reference image or pixel values of an edge image of the display image and pixel values of an edge image of the reference image; and
perform the error detection based on the indicator and the second indicator.
7. The circuit apparatus according to claim 1 ,
wherein the image acquisition circuit is configured to generate the display image by overlaying a second image on the given area of a first image, and
the background image corresponds to the first image.
8. An error detection method comprising:
acquiring a display image including a foreground image in a given area of the display image and a background image corresponding to a background of the foreground image out of the display image;
determining histograms of pixel values of the display image to perform a correlation operation using the histograms;
determining an indicator representing a degree of dissimilarity between the foreground image and the background image based on a result of the correlation operation;
dividing the display image into a plurality of band-shaped areas and divide each of the plurality of band-shaped areas into a plurality of individual areas;
performing fast Fourier transform processing on each edge image of the plurality of individual areas of the display image to obtain a first two-dimensional fast Fourier transform result including a plurality of first spatial frequency components;
performing the fast Fourier transform processing on an edge image of a reference image of the foreground image to obtain a second two-dimensional fast Fourier transform result including a plurality of second spatial frequency components, wherein the plurality of first and second spatial frequency components have the same number of rows and columns;
performing inverse fast Fourier transform processing on the first and second two-dimensional fast Fourier transform results, by comparing every component of the plurality of first spatial frequency components with every corresponding component of the plurality of second spatial frequency components, to obtain an inverse fast Fourier transform result, the inverse fast Fourier transform result corresponding to a first plurality of cross-correlations between every edge image of the plurality of individual areas of the display image and the edge image of the reference image of the foreground image;
generating a second cross-correlation between the display image and the reference image based on the first plurality of cross-correlations;
determining whether the second cross-correlation contains a value that is equal to or more than a threshold value;
detecting a foreground image position where the second cross-correlation contains the value that is equal to or more than the threshold value as a position of the foreground image in the display image;
setting a target area in the display image based on the detected foreground image position, the target area being a rectangular area in which the detected foreground image position is a center thereof and the foreground image is contained; and
performing an error detection with respect to the target area of the display image based on the indicator.