Image coding apparatus and method
View Patent ↗An original image shot by a shooting unit is read in a frame buffer and transformed by a wavelet transformer. An evaluating unit monitors the coefficients of the HL, LH, HH sub-bands generated by the wavelet transformer and checks the number of the high frequency components in the original image. If there are sufficient high frequency components, the quality of the original image is judged to be good, and if not, the image quality is judged not to be good because of camera shake or the like. The evaluating unit sends a coding indication signal to a quantizer if the image quality is good. Thereby the wavelet transformed image is coded. If the image quality is not good, the evaluating unit sends a re-shooting indication signal to the shooting unit.
1. An image coding apparatus comprising:
a spatial filter which conducts a filtering process on an image in such a manner that the whole shot image is handled as a single item;
a coding unit which codes the image on a basis of a processing result produced by the spatial filter; and
an evaluating unit which evaluates the quality of the image according to an amount of high frequency component in the image which is extracted during the filtering process by the spatial filter,
wherein a plurality of images continuously shot are input, and the evaluating unit decides that there is a scene change when a greater amount of change than a predefined one is detected in a distribution of the high frequency component in the images.
2. The apparatus of claim 1 , further comprising a storage control unit which selectively stores into a memory the image which is involved in the scene change.
3. The apparatus of claim 1 , wherein the coding process carried out by the coding unit is conducted on the image which is judged by the evaluating unit to be involved in the scene change.
4. The apparatus of claim 1 , wherein the spatial filter conducts a two-dimensional wavelet transform on the image and the evaluating unit evaluates the quality of the image according to the wavelet transform coefficients of at least one of HL, LH, and HH sub-bands generated from the image by the spatial filter.
5. An image coding apparatus comprising:
a spatial filter which conducts a filtering process on an image in such a manner that the whole shot image is handled as a single item;
a coding unit which codes the image on a basis of a processing result produced by the spatial filter; and
an evaluating unit which evaluates the quality of the image according to an amount of high frequency component in the image which is extracted during the filtering process by the spatial filter,
wherein the evaluating unit judges the quality of the image according to the high frequency component of an important region of the image.
6. The apparatus of claim 5 , wherein a plurality of images continuously shot are input, and the evaluating unit decides that there is a scene change when a greater amount of change than a predefined one is detected in a distribution of the high frequency component in the images.
7. An image coding apparatus comprising:
a spatial filter which conducts a filtering process on an image in such a manner that the whole shot image is handled as a single item;
a coding unit which codes the image on a basis of a processing result produced by the spatial filter; and
an evaluating unit which evaluates the quality of the image according to an amount of high frequency component in the image which is extracted during the filtering process by the spatial filter,
wherein the evaluating unit counts the wavelet transform coefficients within the sub-band, an absolute value of each of which exceeds a predefined value, and evaluates the image quality depending on the count.
8. The apparatus of claim 7 , wherein a plurality of images continuously shot are input, and the evaluating unit decides that there is a scene change when a greater amount of change than a predefined one is detected in a distribution of the high frequency component in the images.
9. An image coding method comprising:
conducting a two-dimensional wavelet transform on the whole shot image;
coding the image on a basis of a result of the two-dimensional wavelet transform; and
evaluating the quality of the image according to an amount of high frequency component in an image extracted in the two-dimensional wavelet transform,
wherein a plurality of images continuously shot are input, and the evaluating unit decides that there is a scene change when a greater amount of change than a predefined one is detected in a distribution of the high frequency component in the images.