Image processing methods and image processing apparatus

An image-processing method for creating processed image data by applying a spatial-filtering processing and either an enlargement or a reduction processing to source image data, under a condition that a magnification factor of either said enlargement or said reduction processing is lower than a predetermined value, comprising the steps of:

• performing a size-varying processing to vary a size of an image up to a predetermined intermediate size established in advance and an angle-rotating processing to rotate an angle of said image up to a first angle value, being a predetermined rotating angle,
• applying said spatial-filtering processing to image data processed by said size-varying processing and said angle-rotating processing;
• and
• performing again said size-varying processing to further vary said size of said image up to an objective size also established in advance and said angle-rotating processing to reversely rotate said angle of said image up to a second angle value, being opposite said first angle value.

An image-processing method, comprising the steps of:

• extracting a plurality of couples of pixels, in each of which two pixels are symmetrically positioned in respect to an objective pixel to be processed through an image-processing;
• calculating differential values between said two pixels and said objective pixel with respect to said plurality of couples of pixels;
• extracting a specific couple of pixels, having a minimum differential value, out of said plurality of couples of pixels;
• and
• setting a weighted-addition average value of three pixels including said specific couple of pixels and said objective pixel concerned, as a new objective pixel.

An image-processing method for processing source image data, comprising the steps of:

• setting a first threshold value predetermined in advance and a maximum radius from a noticed pixel, to be processed by an image-processing, to an objective pixel, being an object for comparison, with respect to said source image data;
• applying a signal-smoothening processing to said source image data on the basis of said first threshold value and a differential value between said noticed pixel and said objective pixel to generate second source image data;
• setting a second threshold value, which is smaller than said first threshold value, and a radius, which is larger than said maximum radius;
• and
• applying again said signal-smoothening processing to said second source image data.

An image-processing method for processing source image data including a plurality of color components, each of which includes data sets of at least three dimensions, one of which represents brightness information, and another two of which represent chrominance coded information, comprising the steps of:

• applying a first spatial-filtering processing to a data set representing said brightness information;
• and
• applying a second spatial-filtering processing to all of said data sets;
• wherein a power for emphasizing a low-spatial frequency region in said second spatial-filtering processing is greater than that in said first spatial-filtering processing.

An image-processing method for creating processed image data by applying a spatial-filtering processing and a size-converting processing in an enlarging direction to source image data, comprising the steps of:

• determining whether an effect of a sharpness-emphasizing processing, to be performed in said spatial-filtering processing, should be relatively strong or weak, based on instructive information in regard to image-processing items inputted in advance;
• and
• applying said spatial-filtering processing at first, and then, said size-converting processing to said source image data, when determining that said effect of said sharpness-emphasizing processing should be relatively strong;
• or
• applying said size-converting processing at first, and then, said spatial-filtering processing to said source image data, when determining that said effect of said sharpness-emphasizing processing should be relatively weak.

An image-processing apparatus for processing an image, comprising:

• an image-inputting section to acquire image data of a source image from an image recording medium or a document having said source image;
• an instructive-information inputting section to input instructive information in regard to image-processing items to be performed in said image-processing apparatus;
• an image-processing section to apply an image-processing to said image data acquired by said image inputting section, so as to create processed image data;
• and
• an image-outputting section to output said image in either a first mode that said processed image data are written onto an information-recording medium, or a second mode that said image is written on an image recording medium to obtain a hardcopy, or a third mode that said image is displayed on an image-displaying device;
• wherein said image-processing section determines whether an effect of a sharpness-emphasizing processing, to be performed in a spatial-filtering processing, should be relatively strong or weak, based on said instructive information in regard to said image-processing items inputted by said instructive-information inputting section;
• and
• wherein said image-processing section applies said spatial-filtering processing at first, and then, said size-converting processing to said image data, when determining that said effect of said sharpness-emphasizing processing should be relatively strong;
• or said image-processing section applies said size-converting processing at first, and then, said spatial-filtering processing to said image data, when determining that said effect of said sharpness-emphasizing processing should be relatively weak.