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Improved HSV conversion
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@radarhere
radarhere committed Aug 2, 2019
1 parent f3f45cf commit 8832636
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Showing 2 changed files with 145 additions and 36 deletions.
1 change: 1 addition & 0 deletions Tests/test_image_convert.py
View file
Expand Up @@ -23,6 +23,7 @@ def convert(im, mode):
"RGBX",
"CMYK",
"YCbCr",
"HSV",
)

for mode in modes:
Expand Down
180 changes: 144 additions & 36 deletions src/libImaging/Convert.c
View file
Expand Up @@ -101,6 +101,19 @@ bit2ycbcr(UINT8* out, const UINT8* in, int xsize)
}
}

static void
bit2hsv(UINT8* out, const UINT8* in, int xsize)
{
int x;
for (x = 0; x < xsize; x++, out += 4) {
UINT8 v = (*in++ != 0) ? 255 : 0;
out[0] = 0;
out[1] = 0;
out[2] = v;
out[3] = 255;
}
}

/* ----------------- */
/* RGB/L conversions */
/* ----------------- */
Expand Down Expand Up @@ -175,6 +188,19 @@ l2rgb(UINT8* out, const UINT8* in, int xsize)
}
}

static void
l2hsv(UINT8* out, const UINT8* in, int xsize)
{
int x;
for (x = 0; x < xsize; x++, out += 4) {
UINT8 v = *in++;
out[0] = 0;
out[1] = 0;
out[2] = v;
out[3] = 255;
}
}

static void
la2l(UINT8* out, const UINT8* in, int xsize)
{
Expand All @@ -196,6 +222,19 @@ la2rgb(UINT8* out, const UINT8* in, int xsize)
}
}

static void
la2hsv(UINT8* out, const UINT8* in, int xsize)
{
int x;
for (x = 0; x < xsize; x++, in += 4, out += 4) {
UINT8 v = in[0];
out[0] = 0;
out[1] = 0;
out[2] = v;
out[3] = in[3];
}
}

static void
rgb2bit(UINT8* out, const UINT8* in, int xsize)
{
Expand Down Expand Up @@ -283,54 +322,58 @@ rgb2bgr24(UINT8* out, const UINT8* in, int xsize)
}

static void
rgb2hsv(UINT8* out, const UINT8* in, int xsize)
rgb2hsv_row(UINT8* out, const UINT8* in)
{ // following colorsys.py
float h,s,rc,gc,bc,cr;
UINT8 maxc,minc;
UINT8 r, g, b;
UINT8 uh,us,uv;
int x;

for (x = 0; x < xsize; x++, in += 4) {
r = in[0];
g = in[1];
b = in[2];

maxc = MAX(r,MAX(g,b));
minc = MIN(r,MIN(g,b));
uv = maxc;
if (minc == maxc){
*out++ = 0;
*out++ = 0;
*out++ = uv;
r = in[0];
g = in[1];
b = in[2];
maxc = MAX(r,MAX(g,b));
minc = MIN(r,MIN(g,b));
uv = maxc;
if (minc == maxc){
uh = 0;
us = 0;
} else {
cr = (float)(maxc-minc);
s = cr/(float)maxc;
rc = ((float)(maxc-r))/cr;
gc = ((float)(maxc-g))/cr;
bc = ((float)(maxc-b))/cr;
if (r == maxc) {
h = bc-gc;
} else if (g == maxc) {
h = 2.0 + rc-bc;
} else {
cr = (float)(maxc-minc);
s = cr/(float)maxc;
rc = ((float)(maxc-r))/cr;
gc = ((float)(maxc-g))/cr;
bc = ((float)(maxc-b))/cr;
if (r == maxc) {
h = bc-gc;
} else if (g == maxc) {
h = 2.0 + rc-bc;
} else {
h = 4.0 + gc-rc;
}
// incorrect hue happens if h/6 is negative.
h = fmod((h/6.0 + 1.0), 1.0);

uh = (UINT8)CLIP8((int)(h*255.0));
us = (UINT8)CLIP8((int)(s*255.0));
h = 4.0 + gc-rc;
}
// incorrect hue happens if h/6 is negative.
h = fmod((h/6.0 + 1.0), 1.0);

*out++ = uh;
*out++ = us;
*out++ = uv;
uh = (UINT8)CLIP8((int)(h*255.0));
us = (UINT8)CLIP8((int)(s*255.0));
}
out[0] = uh;
out[1] = us;
out[2] = uv;
}

}
*out++ = in[3];
static void
rgb2hsv(UINT8* out, const UINT8* in, int xsize)
{
int x;
for (x = 0; x < xsize; x++, in += 4, out += 4) {
rgb2hsv_row(out, in);
out[3] = in[3];
}
}



static void
hsv2rgb(UINT8* out, const UINT8* in, int xsize)
{ // following colorsys.py
Expand Down Expand Up @@ -562,6 +605,22 @@ cmyk2rgb(UINT8* out, const UINT8* in, int xsize)
}
}

static void
cmyk2hsv(UINT8* out, const UINT8* in, int xsize)
{
int x, nk, tmp;
for (x = 0; x < xsize; x++) {
nk = 255 - in[3];
out[0] = CLIP8(nk - MULDIV255(in[0], nk, tmp));
out[1] = CLIP8(nk - MULDIV255(in[1], nk, tmp));
out[2] = CLIP8(nk - MULDIV255(in[2], nk, tmp));
rgb2hsv_row(out, out);
out[3] = 255;
out += 4;
in += 4;
}
}

/* ------------- */
/* I conversions */
/* ------------- */
Expand Down Expand Up @@ -631,6 +690,24 @@ i2rgb(UINT8* out, const UINT8* in_, int xsize)
}
}

static void
i2hsv(UINT8* out, const UINT8* in_, int xsize)
{
int x;
INT32* in = (INT32*) in_;
for (x = 0; x < xsize; x++, in++, out+=4) {
out[0] = 0;
out[1] = 0;
if (*in <= 0)
out[2] = 0;
else if (*in >= 255)
out[2] = 255;
else
out[2] = (UINT8) *in;
out[3] = 255;
}
}

/* ------------- */
/* F conversions */
/* ------------- */
Expand Down Expand Up @@ -861,6 +938,7 @@ static struct {
{ "1", "RGBX", bit2rgb },
{ "1", "CMYK", bit2cmyk },
{ "1", "YCbCr", bit2ycbcr },
{ "1", "HSV", bit2hsv },

{ "L", "1", l2bit },
{ "L", "LA", l2la },
Expand All @@ -871,6 +949,7 @@ static struct {
{ "L", "RGBX", l2rgb },
{ "L", "CMYK", l2cmyk },
{ "L", "YCbCr", l2ycbcr },
{ "L", "HSV", l2hsv },

{ "LA", "L", la2l },
{ "LA", "La", lA2la },
Expand All @@ -879,6 +958,7 @@ static struct {
{ "LA", "RGBX", la2rgb },
{ "LA", "CMYK", la2cmyk },
{ "LA", "YCbCr", la2ycbcr },
{ "LA", "HSV", la2hsv },

{ "La", "LA", la2lA },

Expand All @@ -887,6 +967,7 @@ static struct {
{ "I", "RGB", i2rgb },
{ "I", "RGBA", i2rgb },
{ "I", "RGBX", i2rgb },
{ "I", "HSV", i2hsv },

{ "F", "L", f2l },
{ "F", "I", f2i },
Expand Down Expand Up @@ -915,6 +996,7 @@ static struct {
{ "RGBA", "RGBX", rgb2rgba },
{ "RGBA", "CMYK", rgb2cmyk },
{ "RGBA", "YCbCr", ImagingConvertRGB2YCbCr },
{ "RGBA", "HSV", rgb2hsv },

{ "RGBa", "RGBA", rgba2rgbA },

Expand All @@ -926,10 +1008,12 @@ static struct {
{ "RGBX", "RGB", rgba2rgb },
{ "RGBX", "CMYK", rgb2cmyk },
{ "RGBX", "YCbCr", ImagingConvertRGB2YCbCr },
{ "RGBX", "HSV", rgb2hsv },

{ "CMYK", "RGB", cmyk2rgb },
{ "CMYK", "RGBA", cmyk2rgb },
{ "CMYK", "RGBX", cmyk2rgb },
{ "CMYK", "HSV", cmyk2hsv },

{ "YCbCr", "L", ycbcr2l },
{ "YCbCr", "LA", ycbcr2la },
Expand Down Expand Up @@ -1101,6 +1185,28 @@ pa2rgb(UINT8* out, const UINT8* in, int xsize, const UINT8* palette)
}
}

static void
p2hsv(UINT8* out, const UINT8* in, int xsize, const UINT8* palette)
{
int x;
for (x = 0; x < xsize; x++, out += 4) {
const UINT8* rgb = &palette[*in++ * 4];
rgb2hsv_row(out, rgb);
out[3] = 255;
}
}

static void
pa2hsv(UINT8* out, const UINT8* in, int xsize, const UINT8* palette)
{
int x;
for (x = 0; x < xsize; x++, in += 4, out += 4) {
const UINT8* rgb = &palette[in[0] * 4];
rgb2hsv_row(out, rgb);
out[3] = 255;
}
}

static void
p2rgba(UINT8* out, const UINT8* in, int xsize, const UINT8* palette)
{
Expand Down Expand Up @@ -1192,6 +1298,8 @@ frompalette(Imaging imOut, Imaging imIn, const char *mode)
convert = alpha ? pa2cmyk : p2cmyk;
else if (strcmp(mode, "YCbCr") == 0)
convert = alpha ? pa2ycbcr : p2ycbcr;
else if (strcmp(mode, "HSV") == 0)
convert = alpha ? pa2hsv : p2hsv;
else
return (Imaging) ImagingError_ValueError("conversion not supported");

Expand Down

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