| Method | Description | |
|---|---|---|
| NeedContextRows ( ) : bool | ||
| downsample ( byte input_buf, int in_row_index, byte output_buf, int out_row_group_index ) : void |
Do downsampling for a whole row group (all components). In this version we simply downsample each component independently.
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| jpeg_downsampler ( jpeg_compress_struct cinfo ) |
| Method | Description | |
|---|---|---|
| expand_right_edge ( byte image_data, int startInputRow, int num_rows, int input_cols, int output_cols ) : void |
Expand a component horizontally from width input_cols to width output_cols, by duplicating the rightmost samples.
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| fullsize_downsample ( int componentIndex, byte input_data, int startInputRow, byte output_data, int startOutRow ) : void |
Downsample pixel values of a single component. This version handles the special case of a full-size component, without smoothing.
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| fullsize_smooth_downsample ( int componentIndex, byte input_data, int startInputRow, byte output_data, int startOutRow ) : void |
Downsample pixel values of a single component. This version handles the special case of a full-size component, with smoothing. One row of context is required.
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| h2v1_downsample ( int componentIndex, byte input_data, int startInputRow, byte output_data, int startOutRow ) : void |
Downsample pixel values of a single component. This version handles the common case of 2:1 horizontal and 1:1 vertical, without smoothing. A note about the "bias" calculations: when rounding fractional values to integer, we do not want to always round 0.5 up to the next integer. If we did that, we'd introduce a noticeable bias towards larger values. Instead, this code is arranged so that 0.5 will be rounded up or down at alternate pixel locations (a simple ordered dither pattern).
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| h2v2_downsample ( int componentIndex, byte input_data, int startInputRow, byte output_data, int startOutRow ) : void |
Downsample pixel values of a single component. This version handles the standard case of 2:1 horizontal and 2:1 vertical, without smoothing.
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| h2v2_smooth_downsample ( int componentIndex, byte input_data, int startInputRow, byte output_data, int startOutRow ) : void |
Downsample pixel values of a single component. This version handles the standard case of 2:1 horizontal and 2:1 vertical, with smoothing. One row of context is required.
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| int_downsample ( int componentIndex, byte input_data, int startInputRow, byte output_data, int startOutRow ) : void |
Downsample pixel values of a single component. One row group is processed per call. This version handles arbitrary integral sampling ratios, without smoothing. Note that this version is not actually used for customary sampling ratios.
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| public downsample ( byte input_buf, int in_row_index, byte output_buf, int out_row_group_index ) : void | ||
| input_buf | byte | |
| in_row_index | int | |
| output_buf | byte | |
| out_row_group_index | int | |
| return | void | |
| public jpeg_downsampler ( jpeg_compress_struct cinfo ) | ||
| cinfo | jpeg_compress_struct | |