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CentrED/Imaging/JpegLib/imjdmerge.pas

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unit imjdmerge;
{ This file contains code for merged upsampling/color conversion.
This file combines functions from jdsample.c and jdcolor.c;
read those files first to understand what's going on.
When the chroma components are to be upsampled by simple replication
(ie, box filtering), we can save some work in color conversion by
calculating all the output pixels corresponding to a pair of chroma
samples at one time. In the conversion equations
R := Y + K1 * Cr
G := Y + K2 * Cb + K3 * Cr
B := Y + K4 * Cb
only the Y term varies among the group of pixels corresponding to a pair
of chroma samples, so the rest of the terms can be calculated just once.
At typical sampling ratios, this eliminates half or three-quarters of the
multiplications needed for color conversion.
This file currently provides implementations for the following cases:
YCbCr => RGB color conversion only.
Sampling ratios of 2h1v or 2h2v.
No scaling needed at upsample time.
Corner-aligned (non-CCIR601) sampling alignment.
Other special cases could be added, but in most applications these are
the only common cases. (For uncommon cases we fall back on the more
general code in jdsample.c and jdcolor.c.) }
{ Original: jdmerge.c ; Copyright (C) 1994-1996, Thomas G. Lane. }
interface
{$I imjconfig.inc}
uses
imjmorecfg,
imjinclude,
imjpeglib,
imjutils;
{ Module initialization routine for merged upsampling/color conversion.
NB: this is called under the conditions determined by use_merged_upsample()
in jdmaster.c. That routine MUST correspond to the actual capabilities
of this module; no safety checks are made here. }
{GLOBAL}
procedure jinit_merged_upsampler (cinfo : j_decompress_ptr);
implementation
{ Private subobject }
type { the same definition as in JdColor }
int_Color_Table = array[0..MAXJSAMPLE+1-1] of int;
int_CConvertPtr = ^int_Color_Table;
INT32_Color_Table = array[0..MAXJSAMPLE+1-1] of INT32;
INT32_CConvertPtr = ^INT32_Color_Table;
type
my_upsample_ptr = ^my_upsampler;
my_upsampler = record
pub : jpeg_upsampler; { public fields }
{ Pointer to routine to do actual upsampling/conversion of one row group }
upmethod : procedure (cinfo : j_decompress_ptr;
input_buf : JSAMPIMAGE;
in_row_group_ctr : JDIMENSION;
output_buf : JSAMPARRAY);
{ Private state for YCC->RGB conversion }
Cr_r_tab : int_CConvertPtr; { => table for Cr to R conversion }
Cb_b_tab : int_CConvertPtr; { => table for Cb to B conversion }
Cr_g_tab : INT32_CConvertPtr; { => table for Cr to G conversion }
Cb_g_tab : INT32_CConvertPtr; { => table for Cb to G conversion }
{ For 2:1 vertical sampling, we produce two output rows at a time.
We need a "spare" row buffer to hold the second output row if the
application provides just a one-row buffer; we also use the spare
to discard the dummy last row if the image height is odd. }
spare_row : JSAMPROW;
spare_full : boolean; { TRUE if spare buffer is occupied }
out_row_width : JDIMENSION; { samples per output row }
rows_to_go : JDIMENSION; { counts rows remaining in image }
end; {my_upsampler;}
const
SCALEBITS = 16; { speediest right-shift on some machines }
ONE_HALF = (INT32(1) shl (SCALEBITS-1));
{ Initialize tables for YCC->RGB colorspace conversion.
This is taken directly from jdcolor.c; see that file for more info. }
{LOCAL}
procedure build_ycc_rgb_table (cinfo : j_decompress_ptr);
const
FIX_1_40200 = INT32( Round(1.40200 * (INT32(1) shl SCALEBITS)) );
FIX_1_77200 = INT32( Round(1.77200 * (INT32(1) shl SCALEBITS)) );
FIX_0_71414 = INT32( Round(0.71414 * (INT32(1) shl SCALEBITS)) );
FIX_0_34414 = INT32( Round(0.34414 * (INT32(1) shl SCALEBITS)) );
var
upsample : my_upsample_ptr;
i : int;
x : INT32;
var
shift_temp : INT32;
begin
upsample := my_upsample_ptr (cinfo^.upsample);
upsample^.Cr_r_tab := int_CConvertPtr (
cinfo^.mem^.alloc_small (j_common_ptr (cinfo), JPOOL_IMAGE,
(MAXJSAMPLE+1) * SIZEOF(int)) );
upsample^.Cb_b_tab := int_CConvertPtr (
cinfo^.mem^.alloc_small (j_common_ptr (cinfo), JPOOL_IMAGE,
(MAXJSAMPLE+1) * SIZEOF(int)) );
upsample^.Cr_g_tab := INT32_CConvertPtr (
cinfo^.mem^.alloc_small (j_common_ptr (cinfo), JPOOL_IMAGE,
(MAXJSAMPLE+1) * SIZEOF(INT32)) );
upsample^.Cb_g_tab := INT32_CConvertPtr (
cinfo^.mem^.alloc_small (j_common_ptr (cinfo), JPOOL_IMAGE,
(MAXJSAMPLE+1) * SIZEOF(INT32)) );
x := -CENTERJSAMPLE;
for i := 0 to pred(MAXJSAMPLE) do
begin
{ i is the actual input pixel value, in the range 0..MAXJSAMPLE }
{ The Cb or Cr value we are thinking of is x := i - CENTERJSAMPLE }
{ Cr=>R value is nearest int to 1.40200 * x }
{upsample^.Cr_r_tab^[i] := int(
RIGHT_SHIFT(FIX_1_40200 * x + ONE_HALF, SCALEBITS) );}
shift_temp := FIX_1_40200 * x + ONE_HALF;
if shift_temp < 0 then { SHIFT arithmetic RIGHT }
upsample^.Cr_r_tab^[i] := int((shift_temp shr SCALEBITS)
or ( (not INT32(0)) shl (32-SCALEBITS)))
else
upsample^.Cr_r_tab^[i] := int(shift_temp shr SCALEBITS);
{ Cb=>B value is nearest int to 1.77200 * x }
{upsample^.Cb_b_tab^[i] := int(
RIGHT_SHIFT(FIX_1_77200 * x + ONE_HALF, SCALEBITS) );}
shift_temp := FIX_1_77200 * x + ONE_HALF;
if shift_temp < 0 then { SHIFT arithmetic RIGHT }
upsample^.Cb_b_tab^[i] := int((shift_temp shr SCALEBITS)
or ( (not INT32(0)) shl (32-SCALEBITS)))
else
upsample^.Cb_b_tab^[i] := int(shift_temp shr SCALEBITS);
{ Cr=>G value is scaled-up -0.71414 * x }
upsample^.Cr_g_tab^[i] := (- FIX_0_71414) * x;
{ Cb=>G value is scaled-up -0.34414 * x }
{ We also add in ONE_HALF so that need not do it in inner loop }
upsample^.Cb_g_tab^[i] := (- FIX_0_34414) * x + ONE_HALF;
Inc(x);
end;
end;
{ Initialize for an upsampling pass. }
{METHODDEF}
procedure start_pass_merged_upsample (cinfo : j_decompress_ptr);
var
upsample : my_upsample_ptr;
begin
upsample := my_upsample_ptr (cinfo^.upsample);
{ Mark the spare buffer empty }
upsample^.spare_full := FALSE;
{ Initialize total-height counter for detecting bottom of image }
upsample^.rows_to_go := cinfo^.output_height;
end;
{ Control routine to do upsampling (and color conversion).
The control routine just handles the row buffering considerations. }
{METHODDEF}
procedure merged_2v_upsample (cinfo : j_decompress_ptr;
input_buf : JSAMPIMAGE;
var in_row_group_ctr : JDIMENSION;
in_row_groups_avail : JDIMENSION;
output_buf : JSAMPARRAY;
var out_row_ctr : JDIMENSION;
out_rows_avail : JDIMENSION);
{ 2:1 vertical sampling case: may need a spare row. }
var
upsample : my_upsample_ptr;
work_ptrs : array[0..2-1] of JSAMPROW;
num_rows : JDIMENSION; { number of rows returned to caller }
begin
upsample := my_upsample_ptr (cinfo^.upsample);
if (upsample^.spare_full) then
begin
{ If we have a spare row saved from a previous cycle, just return it. }
jcopy_sample_rows(JSAMPARRAY(@upsample^.spare_row),
0,
JSAMPARRAY(@ output_buf^[out_row_ctr]),
0, 1, upsample^.out_row_width);
num_rows := 1;
upsample^.spare_full := FALSE;
end
else
begin
{ Figure number of rows to return to caller. }
num_rows := 2;
{ Not more than the distance to the end of the image. }
if (num_rows > upsample^.rows_to_go) then
num_rows := upsample^.rows_to_go;
{ And not more than what the client can accept: }
Dec(out_rows_avail, {var} out_row_ctr);
if (num_rows > out_rows_avail) then
num_rows := out_rows_avail;
{ Create output pointer array for upsampler. }
work_ptrs[0] := output_buf^[out_row_ctr];
if (num_rows > 1) then
begin
work_ptrs[1] := output_buf^[out_row_ctr + 1];
end
else
begin
work_ptrs[1] := upsample^.spare_row;
upsample^.spare_full := TRUE;
end;
{ Now do the upsampling. }
upsample^.upmethod (cinfo, input_buf, {var}in_row_group_ctr,
JSAMPARRAY(@work_ptrs));
end;
{ Adjust counts }
Inc(out_row_ctr, num_rows);
Dec(upsample^.rows_to_go, num_rows);
{ When the buffer is emptied, declare this input row group consumed }
if (not upsample^.spare_full) then
Inc(in_row_group_ctr);
end;
{METHODDEF}
procedure merged_1v_upsample (cinfo : j_decompress_ptr;
input_buf : JSAMPIMAGE;
var in_row_group_ctr : JDIMENSION;
in_row_groups_avail : JDIMENSION;
output_buf : JSAMPARRAY;
var out_row_ctr : JDIMENSION;
out_rows_avail : JDIMENSION);
{ 1:1 vertical sampling case: much easier, never need a spare row. }
var
upsample : my_upsample_ptr;
begin
upsample := my_upsample_ptr (cinfo^.upsample);
{ Just do the upsampling. }
upsample^.upmethod (cinfo, input_buf, in_row_group_ctr,
JSAMPARRAY(@ output_buf^[out_row_ctr]));
{ Adjust counts }
Inc(out_row_ctr);
Inc(in_row_group_ctr);
end;
{ These are the routines invoked by the control routines to do
the actual upsampling/conversion. One row group is processed per call.
Note: since we may be writing directly into application-supplied buffers,
we have to be honest about the output width; we can't assume the buffer
has been rounded up to an even width. }
{ Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical. }
{METHODDEF}
procedure h2v1_merged_upsample (cinfo : j_decompress_ptr;
input_buf : JSAMPIMAGE;
in_row_group_ctr : JDIMENSION;
output_buf : JSAMPARRAY);
var
upsample : my_upsample_ptr;
{register} y, cred, cgreen, cblue : int;
cb, cr : int;
{register} outptr : JSAMPROW;
inptr0, inptr1, inptr2 : JSAMPLE_PTR;
col : JDIMENSION;
{ copy these pointers into registers if possible }
{register} range_limit : range_limit_table_ptr;
Crrtab : int_CConvertPtr;
Cbbtab : int_CConvertPtr;
Crgtab : INT32_CConvertPtr;
Cbgtab : INT32_CConvertPtr;
var
shift_temp : INT32;
begin
upsample := my_upsample_ptr (cinfo^.upsample);
range_limit := cinfo^.sample_range_limit;
Crrtab := upsample^.Cr_r_tab;
Cbbtab := upsample^.Cb_b_tab;
Crgtab := upsample^.Cr_g_tab;
Cbgtab := upsample^.Cb_g_tab;
inptr0 := JSAMPLE_PTR(input_buf^[0]^[in_row_group_ctr]);
inptr1 := JSAMPLE_PTR(input_buf^[1]^[in_row_group_ctr]);
inptr2 := JSAMPLE_PTR(input_buf^[2]^[in_row_group_ctr]);
outptr := output_buf^[0];
{ Loop for each pair of output pixels }
for col := pred(cinfo^.output_width shr 1) downto 0 do
begin
{ Do the chroma part of the calculation }
cb := GETJSAMPLE(inptr1^);
Inc(inptr1);
cr := GETJSAMPLE(inptr2^);
Inc(inptr2);
cred := Crrtab^[cr];
{cgreen := int( RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS) );}
shift_temp := Cbgtab^[cb] + Crgtab^[cr];
if shift_temp < 0 then { SHIFT arithmetic RIGHT }
cgreen := int((shift_temp shr SCALEBITS)
or ( (not INT32(0)) shl (32-SCALEBITS)))
else
cgreen := int(shift_temp shr SCALEBITS);
cblue := Cbbtab^[cb];
{ Fetch 2 Y values and emit 2 pixels }
y := GETJSAMPLE(inptr0^);
Inc(inptr0);
outptr^[RGB_RED] := range_limit^[y + cred];
outptr^[RGB_GREEN] := range_limit^[y + cgreen];
outptr^[RGB_BLUE] := range_limit^[y + cblue];
Inc(JSAMPLE_PTR(outptr), RGB_PIXELSIZE);
y := GETJSAMPLE(inptr0^);
Inc(inptr0);
outptr^[RGB_RED] := range_limit^[y + cred];
outptr^[RGB_GREEN] := range_limit^[y + cgreen];
outptr^[RGB_BLUE] := range_limit^[y + cblue];
Inc(JSAMPLE_PTR(outptr), RGB_PIXELSIZE);
end;
{ If image width is odd, do the last output column separately }
if Odd(cinfo^.output_width) then
begin
cb := GETJSAMPLE(inptr1^);
cr := GETJSAMPLE(inptr2^);
cred := Crrtab^[cr];
{cgreen := int ( RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS) );}
shift_temp := Cbgtab^[cb] + Crgtab^[cr];
if shift_temp < 0 then { SHIFT arithmetic RIGHT }
cgreen := int((shift_temp shr SCALEBITS)
or ( (not INT32(0)) shl (32-SCALEBITS)))
else
cgreen := int(shift_temp shr SCALEBITS);
cblue := Cbbtab^[cb];
y := GETJSAMPLE(inptr0^);
outptr^[RGB_RED] := range_limit^[y + cred];
outptr^[RGB_GREEN] := range_limit^[y + cgreen];
outptr^[RGB_BLUE] := range_limit^[y + cblue];
end;
end;
{ Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical. }
{METHODDEF}
procedure h2v2_merged_upsample (cinfo : j_decompress_ptr;
input_buf : JSAMPIMAGE;
in_row_group_ctr : JDIMENSION;
output_buf : JSAMPARRAY);
var
upsample : my_upsample_ptr;
{register} y, cred, cgreen, cblue : int;
cb, cr : int;
{register} outptr0, outptr1 : JSAMPROW;
inptr00, inptr01, inptr1, inptr2 : JSAMPLE_PTR;
col : JDIMENSION;
{ copy these pointers into registers if possible }
{register} range_limit : range_limit_table_ptr;
Crrtab : int_CConvertPtr;
Cbbtab : int_CConvertPtr;
Crgtab : INT32_CConvertPtr;
Cbgtab : INT32_CConvertPtr;
var
shift_temp : INT32;
begin
upsample := my_upsample_ptr (cinfo^.upsample);
range_limit := cinfo^.sample_range_limit;
Crrtab := upsample^.Cr_r_tab;
Cbbtab := upsample^.Cb_b_tab;
Crgtab := upsample^.Cr_g_tab;
Cbgtab := upsample^.Cb_g_tab;
inptr00 := JSAMPLE_PTR(input_buf^[0]^[in_row_group_ctr*2]);
inptr01 := JSAMPLE_PTR(input_buf^[0]^[in_row_group_ctr*2 + 1]);
inptr1 := JSAMPLE_PTR(input_buf^[1]^[in_row_group_ctr]);
inptr2 := JSAMPLE_PTR(input_buf^[2]^[in_row_group_ctr]);
outptr0 := output_buf^[0];
outptr1 := output_buf^[1];
{ Loop for each group of output pixels }
for col := pred(cinfo^.output_width shr 1) downto 0 do
begin
{ Do the chroma part of the calculation }
cb := GETJSAMPLE(inptr1^);
Inc(inptr1);
cr := GETJSAMPLE(inptr2^);
Inc(inptr2);
cred := Crrtab^[cr];
{cgreen := int( RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS) );}
shift_temp := Cbgtab^[cb] + Crgtab^[cr];
if shift_temp < 0 then { SHIFT arithmetic RIGHT }
cgreen := int((shift_temp shr SCALEBITS)
or ( (not INT32(0)) shl (32-SCALEBITS)))
else
cgreen := int(shift_temp shr SCALEBITS);
cblue := Cbbtab^[cb];
{ Fetch 4 Y values and emit 4 pixels }
y := GETJSAMPLE(inptr00^);
Inc(inptr00);
outptr0^[RGB_RED] := range_limit^[y + cred];
outptr0^[RGB_GREEN] := range_limit^[y + cgreen];
outptr0^[RGB_BLUE] := range_limit^[y + cblue];
Inc(JSAMPLE_PTR(outptr0), RGB_PIXELSIZE);
y := GETJSAMPLE(inptr00^);
Inc(inptr00);
outptr0^[RGB_RED] := range_limit^[y + cred];
outptr0^[RGB_GREEN] := range_limit^[y + cgreen];
outptr0^[RGB_BLUE] := range_limit^[y + cblue];
Inc(JSAMPLE_PTR(outptr0), RGB_PIXELSIZE);
y := GETJSAMPLE(inptr01^);
Inc(inptr01);
outptr1^[RGB_RED] := range_limit^[y + cred];
outptr1^[RGB_GREEN] := range_limit^[y + cgreen];
outptr1^[RGB_BLUE] := range_limit^[y + cblue];
Inc(JSAMPLE_PTR(outptr1), RGB_PIXELSIZE);
y := GETJSAMPLE(inptr01^);
Inc(inptr01);
outptr1^[RGB_RED] := range_limit^[y + cred];
outptr1^[RGB_GREEN] := range_limit^[y + cgreen];
outptr1^[RGB_BLUE] := range_limit^[y + cblue];
Inc(JSAMPLE_PTR(outptr1), RGB_PIXELSIZE);
end;
{ If image width is odd, do the last output column separately }
if Odd(cinfo^.output_width) then
begin
cb := GETJSAMPLE(inptr1^);
cr := GETJSAMPLE(inptr2^);
cred := Crrtab^[cr];
{cgreen := int (RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS));}
shift_temp := Cbgtab^[cb] + Crgtab^[cr];
if shift_temp < 0 then { SHIFT arithmetic RIGHT }
cgreen := int((shift_temp shr SCALEBITS)
or ( (not INT32(0)) shl (32-SCALEBITS)))
else
cgreen := int(shift_temp shr SCALEBITS);
cblue := Cbbtab^[cb];
y := GETJSAMPLE(inptr00^);
outptr0^[RGB_RED] := range_limit^[y + cred];
outptr0^[RGB_GREEN] := range_limit^[y + cgreen];
outptr0^[RGB_BLUE] := range_limit^[y + cblue];
y := GETJSAMPLE(inptr01^);
outptr1^[RGB_RED] := range_limit^[y + cred];
outptr1^[RGB_GREEN] := range_limit^[y + cgreen];
outptr1^[RGB_BLUE] := range_limit^[y + cblue];
end;
end;
{ Module initialization routine for merged upsampling/color conversion.
NB: this is called under the conditions determined by use_merged_upsample()
in jdmaster.c. That routine MUST correspond to the actual capabilities
of this module; no safety checks are made here. }
{GLOBAL}
procedure jinit_merged_upsampler (cinfo : j_decompress_ptr);
var
upsample : my_upsample_ptr;
begin
upsample := my_upsample_ptr (
cinfo^.mem^.alloc_small (j_common_ptr(cinfo), JPOOL_IMAGE,
SIZEOF(my_upsampler)) );
cinfo^.upsample := jpeg_upsampler_ptr (upsample);
upsample^.pub.start_pass := start_pass_merged_upsample;
upsample^.pub.need_context_rows := FALSE;
upsample^.out_row_width := cinfo^.output_width * JDIMENSION(cinfo^.out_color_components);
if (cinfo^.max_v_samp_factor = 2) then
begin
upsample^.pub.upsample := merged_2v_upsample;
upsample^.upmethod := h2v2_merged_upsample;
{ Allocate a spare row buffer }
upsample^.spare_row := JSAMPROW(
cinfo^.mem^.alloc_large ( j_common_ptr(cinfo), JPOOL_IMAGE,
size_t (upsample^.out_row_width * SIZEOF(JSAMPLE))) );
end
else
begin
upsample^.pub.upsample := merged_1v_upsample;
upsample^.upmethod := h2v1_merged_upsample;
{ No spare row needed }
upsample^.spare_row := NIL;
end;
build_ycc_rgb_table(cinfo);
end;
end.
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