| 摘要 |
PROBLEM TO BE SOLVED: To enable one-shot focusing operation without using a restoration filter nor increasing a calculation amount involved in restoration processing by performing DCT transformation of image data at an initial focus lens position, calculating an average value of DCT transformation coefficients in every wave number and deciding a focussing position with a wave number having a local minimum value as a defocus parameter. SOLUTION: A lens 1 system is set to a initial focus lens position, an image is photographed, it is divided into RGB digital signals through a front end part 3, an image preprocessor(IPP) part 4, it is inverted into a YUV signal by a YUV converting part 43 and after that, DCT transformation is performed by a DSP core 44. A CPU 6 finds the average value of DCT coefficients in every wave number based on a DCT coefficient undergoing DCT transformation, arranges them in the ascending order of a wave number, searches for a wave number having a local minimum value from an average value string of arranged DCT coefficients and decides the searched wave number as a defocus parameter, i.e., a one-shot AF evaluation value. |
