Coding apparatus capable of recording raw image, control method therefor, and storage medium storing control program therefor
AssigneeCanon Kabushiki Kaisha
InventorKoji Togita
Life of this patent
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Abstract
A coding apparatus capable of improving coding efficiency without calculating a PSNR that is coding distortion. A conversion unit obtains subbands by applying wavelet transform to image data. A control unit decides quantization parameters of the respective subbands within quantization parameter ranges corresponding to image quality modes of the image data. A quantization unit quantizes the subbands obtained by the conversion unit based on the respective quantization parameters decided by the control unit. A coding unit codes quantization image data quantized by the quantization unit.
Claims15
A coding apparatus comprising:
- a memory storing instructions;
- and
- a processor that implements the instructions to execute a plurality of tasks, including:
- a subband obtaining task that obtains subbands by applying wavelet transform to image data;
- a range determining task that determines quantization parameter ranges of the respective subbands of the image data according to image quality modes of the image data, wherein:
- a difference between a maximum value and a minimum value that prescribe each of the quantization parameter ranges decreases as the number of executions of the wavelet transform increases or increases as a bit depth of the image data increases;
- a parameter determining task that determines quantization parameters for the respective subbands of the image data within the quantization parameter ranges;
- a quantizing task that quantizes the subbands of the image data based on the respective quantization parameters;
- and
- a coding task that codes the quantized subbands of the image data.
A control method for a coding apparatus, the control method comprising:
- obtaining subbands by applying wavelet transform to image data;
- determining quantization parameter ranges of the respective subbands of the image data according to image quality modes of the image data, wherein:
- a difference between a maximum value and a minimum value that prescribe each of the quantization parameter ranges decreases as the number of executions of the wavelet transform increases or increases a bit depth of the image data increases;
- determining quantization parameters for the respective subbands of the image data within the quantization parameter ranges;
- quantizing the subbands of the image data based on the respective quantization parameters;
- and
- coding the quantized subbands of the image data.
A non-transitory computer-readable storage medium storing a control program executable by a computer to execute a control method for a coding apparatus, the control method comprising:
- obtaining subbands by applying wavelet transform to image data;
- determining quantization parameter ranges of the respective subbands of the image data according to image quality modes of the image data, wherein:
- a difference between a maximum value and a minimum value that prescribe each of the quantization parameter ranges decreases as the number of executions of the wavelet transform increases or increases as a bit depth of the image data increases;
- determining quantization parameters for the respective subbands of the image data within the quantization parameter ranges;
- quantizing the subbands of the image data based on the respective quantization parameters;
- and
- coding the quantized subbands of the image data.
Dependencies are inferred from the claim text.