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266 lines
20 KiB
266 lines
20 KiB
3 years ago
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;* ======================================================================== *;
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;* TEXAS INSTRUMENTS, INC. *;
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;* *;
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;* IMGLIB DSP Image/Video Processing Library *;
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;* *;
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;* Release: Revision 1.04b *;
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;* CVS Revision: 1.12 Mon Oct 21 15:28:45 2002 (UTC) *;
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;* Snapshot date: 23-Oct-2003 *;
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;* *;
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;* This library contains proprietary intellectual property of Texas *;
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;* Instruments, Inc. The library and its source code are protected by *;
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;* various copyrights, and portions may also be protected by patents or *;
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;* other legal protections. *;
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;* *;
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;* This software is licensed for use with Texas Instruments TMS320 *;
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;* family DSPs. This license was provided to you prior to installing *;
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;* the software. You may review this license by consulting the file *;
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;* TI_license.PDF which accompanies the files in this library. *;
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;* ------------------------------------------------------------------------ *;
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;* Copyright (C) 2003 Texas Instruments, Incorporated. *;
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;* All Rights Reserved. *;
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;* ======================================================================== *;
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;* ======================================================================== *;
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;* Assembler compatibility shim for assembling 4.30 and later code on *;
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;* tools prior to 4.30. *;
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;* ======================================================================== *;
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;* ======================================================================== *;
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;* End of assembler compatibility shim. *;
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;* ======================================================================== *;
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* ========================================================================= *
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* TEXAS INSTRUMENTS, INC. *
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* *
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* NAME *
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* IMG_ycbcr422p_rgb565 -- Planarized YCbCr 4:2:2/4:2:0 to 16-bit *
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* RGB 5:6:5 color space conversion. *
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* *
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* REVISION DATE *
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* 21-Oct-2002 *
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* *
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* USAGE *
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* This function is C callable, and is called according to this *
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* C prototype: *
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* *
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* void IMG_ycbcr422p_rgb565 *
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* ( *
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* const short coeff[5], /* Matrix coefficients. */ *
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* const unsigned char *y_data, /* Luminence data (Y') */ *
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* const unsigned char *cb_data, /* Blue color-diff (B'-Y') */ *
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* const unsigned char *cr_data, /* Red color-diff (R'-Y') */ *
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* unsigned short *
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* *restrict rgb_data, /* RGB 5:6:5 packed pixel out. */ *
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* unsigned num_pixels /* # of luma pixels to process */ *
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* ); *
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* *
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* The 'coeff[]' array contains the color-space-conversion matrix *
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* coefficients. The 'y_data', 'cb_data' and 'cr_data' pointers *
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* point to the separate input image planes. The 'rgb_data' pointer *
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* *
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* The kernel is designed to process arbitrary amounts of 4:2:2 *
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* image data, although 4:2:0 image data may be processed as well. *
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* For 4:2:2 input data, the 'y_data', 'cb_data' and 'cr_data' *
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* arrays may hold an arbitrary amount of image data, including *
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* multiple scan lines of image data. *
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* *
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* For 4:2:0 input data, only a single scan-line (or portion *
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* thereof) may be processed at a time. This is achieved by *
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* calling the function twice using the same row data for *
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* 'cr_data' and 'cb_data', and providing new row data for *
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* 'y_data'. This is numerically equivalent to replicating the Cr *
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* and Cb pixels vertically. *
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* *
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* The coefficients in the coeff array must be in signed Q13 form. *
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* These coefficients correspond to the following matrix equation: *
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* *
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* [ coeff[0] 0.0000 coeff[1] ] [ Y' - 16 ] [ R'] *
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* [ coeff[0] coeff[2] coeff[3] ] * [ Cb - 128 ] = [ G'] *
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* [ coeff[0] coeff[4] 0.0000 ] [ Cr - 128 ] [ B'] *
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* *
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* The output from this kernel is 16-bit RGB in 5:6:5 format. *
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* The RGB components are packed into halfwords as shown below. *
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* *
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* 15 11 10 5 4 0 *
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* +----------+----------+----------+ *
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* | Red | Green | Blue | *
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* +----------+----------+----------+ *
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* *
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* This kernel can also return the red, green, and blue values in *
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* the opposite order if a particular application requires it. *
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* This is achieved by exchanging the 'cb_data' and 'cr_data' *
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* arguments when calling the function, and by reversing the order *
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* of coefficients in coeff[1] through coeff[4]. This essentially *
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* implements the following matrix multiply: *
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* *
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* [ coeff[0] 0.0000 coeff[4] ] [ Y' - 16 ] [ B'] *
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* [ coeff[0] coeff[3] coeff[2] ] * [ Cr - 128 ] = [ G'] *
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* [ coeff[0] coeff[1] 0.0000 ] [ Cb - 128 ] [ R'] *
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* *
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* The reversed RGB ordering output by this mode is as follows: *
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* *
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* 15 11 10 5 4 0 *
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* +----------+----------+----------+ *
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* | Blue | Green | Red | *
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* +----------+----------+----------+ *
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* *
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* DESCRIPTION *
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* This kernel performs Y'CbCr to RGB conversion. From the Color *
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* FAQ, http://home.inforamp.net/~poynton/ColorFAQ.html : *
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* *
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* Various scale factors are applied to (B'-Y') and (R'-Y') *
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* for different applications. The Y'PbPr scale factors are *
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* optimized for component analog video. The Y'CbCr scaling *
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* is appropriate for component digital video, JPEG and MPEG. *
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* Kodak's PhotoYCC(tm) uses scale factors optimized for the *
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* gamut of film colors. Y'UV scaling is appropriate as an *
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* intermediate step in the formation of composite NTSC or PAL *
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* video signals, but is not appropriate when the components *
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* are keps separate. Y'UV nomenclature is now used rather *
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* loosely, and it sometimes denotes any scaling of (B'-Y') *
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* and (R'-Y'). Y'IQ coding is obsolete. *
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* *
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* This code can perform various flavors of Y'CbCr to RGB *
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* conversion as long as the offsets on Y, Cb, and Cr are -16, *
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* -128, and -128, respectively, and the coefficients match the *
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* pattern shown. *
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* *
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* The kernel implements the following matrix form, which involves 5 *
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* unique coefficients: *
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* *
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* [ coeff[0] 0.0000 coeff[1] ] [ Y' - 16 ] [ R'] *
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* [ coeff[0] coeff[2] coeff[3] ] * [ Cb - 128 ] = [ G'] *
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* [ coeff[0] coeff[4] 0.0000 ] [ Cr - 128 ] [ B'] *
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* *
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* *
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* Below are some common coefficient sets, along with the matrix *
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* equation that they correspond to. Coefficients are in signed *
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* Q13 notation, which gives a suitable balance between precision *
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* and range. *
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* *
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* 1. Y'CbCr -> RGB conversion with RGB levels that correspond to *
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* the 219-level range of Y'. Expected ranges are [16..235] for *
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* Y' and [16..240] for Cb and Cr. *
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* *
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* coeff[] = { 0x2000, 0x2BDD, -0x0AC5, -0x1658, 0x3770 }; *
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* *
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* [ 1.0000 0.0000 1.3707 ] [ Y' - 16 ] [ R'] *
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* [ 1.0000 -0.3365 -0.6982 ] * [ Cb - 128 ] = [ G'] *
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* [ 1.0000 1.7324 0.0000 ] [ Cr - 128 ] [ B'] *
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* *
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* 2. Y'CbCr -> RGB conversion with the 219-level range of Y' *
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* expanded to fill the full RGB dynamic range. (The matrix *
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* has been scaled by 255/219.) Expected ranges are [16..235] *
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* for Y' and [16..240] for Cb and Cr. *
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* *
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* coeff[] = { 0x2543, 0x3313, -0x0C8A, -0x1A04, 0x408D }; *
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* *
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* [ 1.1644 0.0000 1.5960 ] [ Y' - 16 ] [ R'] *
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* [ 1.1644 -0.3918 -0.8130 ] * [ Cb - 128 ] = [ G'] *
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* [ 1.1644 2.0172 0.0000 ] [ Cr - 128 ] [ B'] *
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* *
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* 3. Y'CbCr -> BGR conversion with RGB levels that correspond to *
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* the 219-level range of Y'. This is equivalent to #1 above, *
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* except that the R, G, and B output order in the packed *
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* pixels is reversed. Note: The 'cr_data' and 'cb_data' *
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* input arguments must be exchanged for this example as *
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* indicated under USAGE above. *
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* *
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* coeff[] = { 0x2000, 0x3770, -0x1658, -0x0AC5, 0x2BDD }; *
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* *
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* [ 1.0000 0.0000 1.7324 ] [ Y' - 16 ] [ B'] *
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* [ 1.0000 -0.6982 -0.3365 ] * [ Cr - 128 ] = [ G'] *
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* [ 1.0000 1.3707 0.0000 ] [ Cb - 128 ] [ R'] *
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* *
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* 4. Y'CbCr -> BGR conversion with the 219-level range of Y' *
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* expanded to fill the full RGB dynamic range. This is *
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* equivalent to #2 above, except that the R, G, and B output *
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* order in the packed pixels is reversed. Note: The *
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* 'cr_data' and 'cb_data' input arguments must be exchanged *
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* for this example as indicated under USAGE above. *
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* *
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* coeff[] = { 0x2000, 0x408D, -0x1A04, -0x0C8A, 0x3313 }; *
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* *
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* [ 1.0000 0.0000 2.0172 ] [ Y' - 16 ] [ B'] *
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* [ 1.0000 -0.8130 -0.3918 ] * [ Cr - 128 ] = [ G'] *
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* [ 1.0000 1.5960 0.0000 ] [ Cb - 128 ] [ R'] *
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* *
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* Other scalings of the color differences (B'-Y') and (R'-Y') *
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* (sometimes incorrectly referred to as U and V) are supported, as *
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* long as the color differences are unsigned values centered around *
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* 128 rather than signed values centered around 0, as noted above. *
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* *
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* In addition to performing plain color-space conversion, color *
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* saturation can be adjusted by scaling coeff[1] through coeff[4]. *
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* Similarly, brightness can be adjusted by scaling coeff[0]. *
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* General hue adjustment can not be performed, however, due to the *
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* two zeros hard-coded in the matrix. *
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* *
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* TECHNIQUES *
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* Pixel replication is performed implicitly on chroma data to *
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* reduce the total number of multiplies required. The chroma *
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* portion of the matrix is calculated once for each Cb, Cr pair, *
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* and the result is added to both Y' samples. *
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* *
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* Matrix Multiplication is performed as a combination of MPY2s and *
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* DOTP2s. Saturation to 8bit values is performed using SPACKU4 *
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* which takes in 4 signed 16-bit values and saturates them to *
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* unsigned 8-bit values. The output of Matrix Multiplication would *
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* ideally be in a Q13 format. This however, cannot be fed directly *
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* to SPACKU4. *
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* *
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* This implies a shift left by 3 bits, which could be pretty *
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* expensive in terms of the number of shifts to be performed. Thus, *
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* to avoid being bottlenecked by so many shifts, the Y, Cr & Cb data *
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* are shifted left by 3 before multiplication. This is possible *
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* because they are 8-bit unsigned data. Due to this, the output of *
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* Matrix Multiplication is in a Q16 format, which can be directly *
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* fed to SPACKU4. *
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* *
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* Because the loop accesses four different arrays at three *
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* different strides, no memory accesses are allowed to parallelize *
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* in the loop. No bank conflicts occur, as a result. *
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* *
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* The epilog has been completely removed, while the prolog is left *
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* as is. However, some cycles of the prolog are performed using the *
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* kernel cycles to help reduce code-size. The setup code is merged *
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* along with the prolog for speed. *
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* *
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* ASSUMPTIONS *
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* The number of luma samples to be processed needs to be a multiple *
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* of 8. *
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* The input Y array needs to be double-word aligned. *
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* The input Cr and Cb arrays need to be word aligned *
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* The output image must be double-word aligned. *
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* *
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* NOTES *
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* No bank conflicts occur. *
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* *
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* Codesize is 952 bytes. *
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* *
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* Memory bank conflicts will not occurs since the 3 loads and two *
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* stores happen in different cycles of the loop *
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* *
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* The kernel requires 3 words of stack space. *
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* *
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* CYCLES *
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* 12 * num_pixels/8 + 50 *
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* *
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* CODESIZE *
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* 952 bytes *
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* *
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* SOURCE *
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* Poynton, Charles et al. "The Color FAQ," 1999. *
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* http://home.inforamp.net/~poynton/ColorFAQ.html *
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* ------------------------------------------------------------------------- *
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* Copyright (c) 2003 Texas Instruments, Incorporated. *
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* All Rights Reserved. *
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* ========================================================================= *
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.global _IMG_ycbcr422p_rgb565
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* ========================================================================= *
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* End of file: img_ycbcr422p_rgb565.h64 *
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* ------------------------------------------------------------------------- *
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* Copyright (c) 2003 Texas Instruments, Incorporated. *
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* All Rights Reserved. *
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* ========================================================================= *
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