Method of identifying image frames suitable for printing

A method of identifying one or more image frames from a series of image frames, the method including the steps of:

• n) calculating, for each image frame in the series a single scalar gradient value characterizing said each image frame, thereby to generate a raw data series;
• o) defining a gradient value threshold;
• p) identifying sets of adjacent gradient values in the raw data series which exceed the gradient value threshold and are of similar value;
• and
• q) selecting a representative image frame from each set of adjacent gradient values.

An apparatus for identifying one or more image frames from a series of video image frames for printing, storing or flagging, the apparatus comprising:

• gradient calculation means arranged to receive a series of image frames and to calculate for each image frame in the series, a single scalar gradient value, and output a raw data series of scalar gradient values, one gradient value characterizing said each frame;
• data smoothing means responsive to the raw data series and arranged to generate and output a smoothed data series;
• identification means responsive to the smoothed data series and arranged to identify and output one or more local maxima in the smoothed data series;
• gradient peak selection means responsive to the one or more local maxima and to the raw data series and arranged to identify one or more gradient value peaks in a corresponding range of the raw data series based upon positions of respective local maxima;
• and
• image frame selection means responsive to the series of image frames and to the identified gradient value peaks, and arranged to select image frames corresponding to each of the identified gradient value peaks.

An apparatus for identifying one or more image frames from a series of image frames, the apparatus comprising:

• means for calculating, for each image frame in the series, a single scalar gradient value characterizing said each image frame, thereby to generate a raw data series;
• means for defining a gradient value threshold;
• means for identifying sets of adjacent gradient values in the raw data series which exceed the gradient value threshold and are of similar value;
• and
• means for selecting a representative image frame from each set of adjacent gradient values.

An apparatus for identifying one or more image frames from a series of video images for printing, storing or flagging, the apparatus comprising:

• gradient calculation means arranged to receive a series of image frames and to calculate, for each image frame in the series, a single scalar gradient value, and output a corresponding series of scalar gradient values characterizing the image frames;
• data smoothing means responsive to the series of gradient values for generating a smoothed data series;
• and
• image frame selection means responsive to the smoothed data series for selecting image frames.

A computer program product including a computer readable medium having recorded thereon a computer program for identifying one or more image frames from a series of video image frames for printing, storing or flagging, the computer program comprising:

• gradient calculation process steps arranged to receive a series of image frames and to calculate, for each image frame in the series, a single scalar gradient value, and output a raw data series of scalar gradient values, one gradient value characterizing said each frame;
• data smoothing process steps responsive to the raw data series and arranged to generate and output a smoothed data series;
• identification process steps responsive to the smoothed data series and arranged to identify and output one or more local maxima in the smoothed data series;
• gradient peak selection process steps responsive to the one or more local maxima and to the raw data series and arranged to identify one or more gradient value peaks in a corresponding range of the raw data series based upon positions of respective local maxima;
• and
• image frame selection process steps responsive to the series of image frames and to the identified gradient value peaks, and arranged to select image frames corresponding to each of the identified gradient value peaks.

A computer program product including a computer readable medium having recorded thereon a computer program for identifying one or more image frames from a series of video image frames for printing, storing or flagging, the computer program comprising:

• process steps for calculating, for each image frame in the series, a single scalar gradient value characterizing said each image frame, thereby to generate a raw data series;
• process steps for defining a gradient value threshold;
• process steps for identifying sets of adjacent gradient values in the raw data series which exceed the gradient value threshold and are of similar value;
• and
• process steps for selecting a representative image frame from each set of adjacent gradient values.