Image processing apparatus

Abstract

An image processing apparatus is provided which offers higher versatility than conventional image processing apparatuses. When an input signal to a spatial filtering block is a monochrome signal that contains Y component only, a selector selects its input terminal and a selector selects its input terminal. Then, a low-pass filter output signal of a programmable spatial filter is inputted to a spatial filter, and a low-pass filter output signal of the spatial filer is inputted to a spatial filter. That is, the programmable spatial filter and the spatial filters are connected in series (in cascade), and the cascade-connected three spatial filters perform filtering operation. In this example, low-pass filters with 5×5 taps are connected in cascade in three stages, which enables low-pass filtering with 13×13 taps.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to image processing apparatuses, and particularly to an image processing apparatus having a plurality of image processing blocks that are capable of real-time processing of an image signal inputted from outside.[0003]2. Description of the Background Art[0004]For an image input apparatus such as a digital still camera, Japanese Patent Application Laid-Open No. 2000-236473 discloses a conventional image processing apparatus including an imaging device, an analog signal processing circuit connected to the imaging device, and a Real-time Processing Unit (RPU) connected to the analog signal processing circuit, where the RPU is capable of processing in a real-time manner an image signal outputted from the analog signal processing circuit.[0005]However, this conventional image processing apparatus does not offer sufficient versatility in the following points:[0006]the number of taps of spatial fil...

AI Technical Summary

Benefits of technology

[0016]According to this configuration, when the input signal is a monochrome signal, the plurality of spatial filters, connected in series, perform spatial filtering operation. Thus, an extra spatial filter that is originally not related to the processing of monochrome signals can be utilized to achieve filtering operation using spatial filter with a larger number of taps. Also, the total processing time can be shorter than when a filtering operation using the same spatial filter is repeated multiple times.

[0028]According to this configuration, the two-dimensional lookup table is connected to follow the color-space transformation circuit that outputs two-channel color signals. The color-space transformation block performs color-space transformation by real-time processing. When the color-space transformation is performed using a three-dimensional lookup table that involves large amounts of calculations, the processing in the three-dimensional lookup table forms a bottleneck to delay the entire processing. Also, a three-dimensional lookup table involves a very large circuit scale. In contrast, using a two-dimensional lookup table avoids increased circuit scale and achieves high-speed color-space transformation without delaying the entire processing.

Problems solved by technology

However, this conventional image processing apparatus does not offer sufficient versatility in the following points:

it is not possible to obtain a high-frequency component when the spatial filter is set not as a high-pass filter;

it is not possible to obtain a mixture signal, such as a signal containing center pixel signal and low-frequency component at a desired ratio, as an output signal from the spatial filter;

image quality is considerably deteriorated when a divergence occurs between a pixel as a source of generation of feature data for modulation and a pixel as a target of modulation of luminance signal;

image quality is considerably deteriorated when a divergence occurs between a pixel as a source of generation of feature data for modulation and a pixel as a target of modulation of color signal;

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