Image encoding apparatus and control method therefor

A control method for an image encoding apparatus for encoding moving image data captured by an image capturing unit, the method comprising:

• generating, from RAW image data of one frame of the moving image data, data of a plurality of planes each formed from a single component, wherein pixels in the RAW image data are arrayed in a Bayer pattern;
• generating, for each plane, coefficient data of a plurality of subbands by performing frequency conversion for the data of a plane of interest;
• quantizing, for each plane, the coefficient data included in a block having a predetermined size with a subband using a quantization parameter for the block of a plane of interest;
• generating, for each plane, encoded data by encoding the quantized coefficient data of the block of a plane of interest;
• and
• updating, for each plane, the quantization parameter used in the quantizing so that a code amount of the generated encoded data becomes equal to a target code amount set for a plane of interest,
• wherein when the blocks of interest of the plurality of planes are encoded, the quantization parameter is updated in the updating by performing steps comprising
• (a) calculating a total code amount difference by summing plane code amount differences of the plurality of planes, where each of the plane code amount differences is, in one plane of the plurality of planes, an integrated difference between a code amount of the encoded data from a first block to a block immediately before the block of interest and a target amount from the first block to the block immediately before the block of interest of the one plane,
• (b) distributing the total code amount difference, as distribution values, to the plurality of planes, where the distribution values are calculated by dividing the total code amount difference in accordance with predetermined distribution ratios defined for the plurality of planes, and
• (c) updating, for each plane, the quantization parameter of the block of interest by adding a value corresponding to the distribution value to the quantization parameter.

A non-transitory computer-readable storage medium storing a program which, when read and executed by a computer, causes the computer to execute:

• generating, from RAW image data of one frame of moving image data, data of a plurality of planes each formed from a single component, wherein pixels in the RAW image data are arrayed in a Bayer pattern;
• generating, for each plane, coefficient data of a plurality of subbands by performing frequency conversion for the data of a plane of interest;
• quantizing, for each plane, the coefficient data included in a block having a predetermined size with a subband, using a quantization parameter for the block of a plane of interest;
• generating, for each plane, encoded data by encoding the quantized coefficient data of the block of a plane of interest;
• and
• updating, for each plane, the quantization parameter used in the quantizing so that a code amount of the generated encoded data becomes equal to a target code amount set for a plane of interest,
• wherein when the blocks of interest of the plurality of planes are encoded, the quantization parameter is updated in the updating by performing steps comprising
• (a) calculating a total code amount difference by summing plane code amount differences of the plurality of planes, where each of the plane code amount differences is, in one plane of the plurality of planes, an integrated difference between a code amount of the encoded data from a first block to a block immediately before the block of interest and a target amount from the first block to the block immediately before the block of interest of the one plane,
• (b) distributing the total code amount difference, as distribution values, to the plurality of planes, where the distribution values are calculated by dividing the total code amount difference in accordance with predetermined distribution ratios defined for the plurality of planes, and
• (c) updating, for each plane, the quantization parameter of the block of interest by adding a value corresponding to the distribution value to the quantization parameter.