Electronic still camera utilizing image compression and digital storage

An electronic still camera employing digital processing of image signals corresponding to a still image and storage of the processed image signals in a removable digital memory, said camera including an area image sensor having a two-dimensional array of photosites corresponding to picture elements of the image and means for exposing said sensor to image light so that analog image signals are obtained from the respective photosites, said camera comprising:

• an A/D converter for converting the analog image signals into digital image signals;
• a digital processor for processing the digital image signals through a compression algorithm and for generating a stream of compressed signals having a variable bit length dependent upon the character of the image, said processor allocating a variable-length memory space in said removable digital memory for each image;
• means for downloading the compressed signals to the allocated image space such that consecutive memory spaces may differ in length depending on the character of each image;
• and
• means for generating a warning signal when the remaining unused memory space in said removable digital memory corresponds to a predetermined amount of memory space generally suitable for at least one more still image.

An electronic still camera employing digital processing of image signals corresponding to a still image and storage of the processed image signals in a removable digital memory, said camera including an area image sensor having a two-dimensional array of photosites corresponding to picture elements of the image and means for exposing said sensor to image light so that analog image signals are obtained from the respective photosites, said camera comprising:

• an A/D converter for converting the analog image signals into digital image signals;
• a random access image buffer having memory space sufficient for a plurality of still images;
• control means responsive to repeated actuation of said exposing means for entering the digital image signals corresponding to a sequence of still images into said image buffer at a rate commensurate with normal operation of the camera, said control means intermittently disabling and reenabling said exposing means according to the memory space remaining in said random access image buffer;
• a digital processor for compressing the digital image signals, said processor connected to said buffer for operating on stored digital signals from the first stored image irregardless of the entering of digital signals corresponding to subsequent still images into said buffer;
• and
• means responsive to said digital processor for downloading the compressed image signals to said removable digital memory.

Electronic still imaging apparatus employing digital processing of image signals corresponding to a still image and storage of the processed image signals in a removable digital memory, said imaging apparatus including an area image sensor having a two-dimensional array of photosites corresponding to picture elements of the image and means for exposing said sensor to image light so that analog image information is generated in respective photosites, said imaging apparatus comprising:

• means for converting the analog image information into digital image signals corresponding to the picture elements;
• an image buffer with storage capacity for storing digital image signals corresponding to a plurality of still images;
• control processor means responsive to user instructions for initiating operation of said exposing means, for clocking the image information from said sensor, and for controlling said converting means to deliver said digital signals to said image buffer, said control processor means loading digital image signals corresponding to said plurality of still images into said image buffer at an input rate commensurate with normal operation of the camera;
• digital processing means for operating on blocks of stored digital image signals at a processing throughput rate different than said input rate, said digital processing means including means for transforming blocks of digital image signals into corresponding sets of transform coefficient signals and for encoding the transform coefficient signals into a compressed stream of processed digital image signals;
• means responsive to said digital processing means for downloading the processed image signals to said removable digital memory;
• and
• diagnostic means for checking the removable digital memory for faults or defects.

Electronic still imaging apparatus employing digital processing of image signals corresponding to a still image and storage of the processed image signals in a removable digital memory, said imaging apparatus including an area image sensor having a two-dimensional array of photosites corresponding to picture elements of the image and means for exposing said sensor to image light so that analog image information is generated in respective photosites, said imaging apparatus comprising:

• means for converting the analog image information into digital image signals corresponding to the picture elements;
• an image buffer for storing one or more blocks of digital image signals corresponding to portions of a still image;
• control processor means responsive to user instructions for initiating operation of said exposing means, for clocking the image information from said sensor, and for controlling said converting means to deliver said digital signals to said image buffer;
• digital processing means for operating on each block of stored digital image signals, said digital processing means including means for transforming each block of digital image signals into corresponding sets of transform coefficient signals and for encoding the transform coefficient signals into a compressed stream of processed digital image signals;
• diagnostic means for checking the removable digital memory for faults or defects and for providing an indication thereof;
• and
• means responsive to said digital processing means and to said indication from said diagnostic means for downloading the processed image signals to said removable digital memory.

Electronic still imaging apparatus employing digital processing of image signals corresponding to a still image and storage of the processed image signals in a removable digital memory, said imaging apparatus including an area image sensor having a two-dimensional array of photosites corresponding to picture elements of the image and means for exposing said sensor to image light so that analog image information is generated in respective photosites, said area image sensor including a color filter array having a multi-colored pattern oriented to said photosites and including one color representative of luminance, said imaging apparatus comprising:

• means for converting the analog image information into digital image signals corresponding to the picture elements;
• an image buffer with storage capacity for storing digital image signals corresponding to a plurality of still images;
• control processor means responsive to user instructions for initiating operation of said exposing means, for clocking the image information from said sensor, and for controlling said converting means to deliver said digital signals to said image buffer, said control processor means loading digital image signals corresponding to said plurality of still images into said image buffer at an input rate commensurate with normal operation of the camera;
• digital processing means for operating on blocks of stored digital image signals at a processing throughput rate different than said input rate, said digital processing means including means for transforming blocks of digital image signals into corresponding sets of transform coefficient signals and for encoding the transform coefficient signals into a compressed stream of processed digital image signals, said digital processing means interpolating at least the luminance component over the block area and transforming each block of digital signals including the interpolated signals;
• and
• means responsive to said digital processing means for downloading the processed image signals to said removable digital memory.