JPEG decoder capable of scaling and scaling method using the same
AssigneeSiliconfile Technologies Inc.
InventorsJae Oh Shim, Jogn Phil Kim
Life of this patent
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Abstract
A JPEG decoder having a scaling function includes an inverse discrete cosine transform block, wherein the JPEG decoder selectively performs an inverse discrete cosine transform on a part of pixel data of a macroblock through the inverse discrete cosine transform block and outputs a scaled image file. The JPEG decoder and the scaling method using the JPEG decoder increase a decoding speed, thereby enabling an image to be output in real time, especially when the JPEG decoder and/or the scaling method are applied to a mobile field. Also, the JPEG decoder and the scaling method using the JPEG decoder can achieve an efficient scaling, even without a separate circuit for scaling, thereby reducing a circuit size and the number of components.
Claims10
A JPEG decoder having a scaling function, the JPEG decoder comprising a dequantization block and an integrated inverse discrete cosine transform (IDCT) block, wherein the JPEG decoder is configured to perform an IDCT on a part of pixel data of a macroblock using the integrated IDCT block to control capacity and resolution of a resultant image file when decoding encoded data, and to output the decoded and scaled image file,
- wherein the dequantization block is configured to:
- dequantize at least a portion of pixel data of a macroblock;
- select, based on a scaling control signal, dequantized pixel data of the macroblock to output to the IDCT block;
- and
- output the selected pixel data to the IDCT block,
- wherein the IDCT block comprises a first IDCT unit, an orthogonal transform unit, and a second IDCT unit,
- wherein the first IDCT unit is configured to:
- select, based on the scaling control signal, pixel data output from the dequantization block comprising one or more selected columns among multiple columns of the macroblock such that a first IDCT is only performed on a portion of the columns of the macroblock, wherein when more than one column is selected to perform the first IDCT, no selected column is adjacent to another selected column;
- and
- perform the first IDCT on the selected pixel data output from the dequantization block;
- wherein the orthogonal transform unit is configured to perform an orthogonal transform on the pixel data subjected to the first IDCT to transpose rows and columns of the macroblock, and
- wherein the second IDCT unit is configured to:
- select, based on the scaling control signal, only data of one or more selected columns among multiple columns output from the orthogonal transform unit such that a second IDCT is only performed on a portion of the columns of the macroblock, wherein when more than one column is selected to perform the second IDCT, no selected column is adjacent to another selected column, further wherein only rows within the selected column which were subjected to the first IDCT are subjected to the second IDCT such that the number of columns subjected to the first IDCT equals the number of rows per column that are subjected to the second IDCT;
- and
- perform the second IDCT on the selected only a portion of the orthogonally transformed pixel data subjected to the first IDCT.
A scaling method of a JPEG decoder, wherein the JPEG decoder comprises a dequantization block and an integrated inverse discrete cosine transform (IDCT) block, wherein the IDCT block comprises a first IDCT unit, an orthogonal transform unit, and a second IDCT unit, the method comprising:
- (a) outputting encoded data as serial data through variable length decoding;
- (b) re-ordering the serial data in an 8×8 macroblock, which is a two-dimensional arrangement format;
- (c) dequantizing, by the dequantization block, at least a portion of pixel data of the 8 ×8 macroblock;
- (d) selecting, by the dequantization block and based on a scaling control signal, dequantized pixel data of the macroblock to output to the IDCT block;
- (e) outputting, by the dequantization block, the selected pixel data to the IDCT block;
- (f) selecting, by the first IDCT unit and based on the scaling control signal, pixel data output from the dequantization block to transform;
- (g) performing, by the first IDCT unit, a first IDCT on the selected pixel data output from the dequantization block comprising at least a first column and a second column which is selected from among eight columns such that no selected column is adjacent to another selected column;
- (h) performing, by the orthogonal transform unit, an orthogonal transform on the pixel data subjected to the first IDCT;
- (i) following step (h), selecting, by the second IDCT unit and based on the scaling control signal, at least a third column and a fourth column which is selected from among eight columns such that no selected column is adjacent to another selected column;
- and
- (j) performing, by the second IDCT unit, a second IDCT on only data within the selected columns that overlaps with data having been subjected to the first IDCT.
Dependencies are inferred from the claim text.