Øyvind Kolås [Tue, 6 Aug 2019 11:46:35 +0000 (13:46 +0200)]
meson: stop overriding libdir
Let meson do it's defaults, this mean we get installed in
prefix/lib/x86_64-linux-gnu/ instead of prefix/lib/
apparently which apparently is better - but different from
what autotools used to do; and leads to other paths also
needing potential adjustment.
Øyvind Kolås [Fri, 2 Aug 2019 11:53:44 +0000 (13:53 +0200)]
build: issue #41 builds without mmx/sse etc extensions do not work
The warnings about the SIMD flags specific variables not being set goes
away with this commit. Setting empty strings do not work since then gcc
ends up looking for input files that are the empty string, thus this patch
re-adds -Wall instead of setting an empty string.
This silences a false warning from gcc, where it doesn't recognize the type
of control flow occuring with the pre/post switches in the reference
conversion.
Add AVX2 conversions from Y float, YA float, RGB float, and RGBA
float, to Y' u8, Y'A u8, R'G'B' u8, and R'G'B'A u8, respectively.
The conversions use a lookup table, similarly to the two-table
conversions, indexed using AVX2's 256-bit gather instruction, which
allow us to process 8 floats at once. Over here, this conversion
is ~5x faster than the SSE conversions.
Note, however, that unlike two-table, we don't use a second
"feedback" table to correct the result, leading to an off-by-one
conversion error with a probability of ~0.1%, using a 2^16-element
table. This error rate is low enough for babl to use the
conversion, but might still be a bit too high regardless; it can be
further reduced with a bigger table.
babl: make model_is_symmetric test adapt tolerance for high values
When the values used are in the billions, the tolerance that originally
was mostly intended for values in the range 0.0-1.0 and its neighborhood
break apart - use 1% of component values as symmetry threshold for such
values.
Elle Stone [Sat, 29 Jun 2019 16:45:34 +0000 (12:45 -0400)]
Add Yu'v' (CIE 1976 UCS) to babl CIE color spaces
Yu'v' is a linear transform of xyY that is more perceptually
uniform, and well-suited for eg creating chromaticity diagrams
that aren't misleading when comparing various RGB color spaces.
This color space has been recommended by many people as a better
choice than xyY. ACES documentation already uses this color space.
Øyvind Kolås [Thu, 13 Jun 2019 15:00:23 +0000 (17:00 +0200)]
babl: symmetric conversions between associated and separate alpha.
Provide symmetric, color data preserving conversions between associated and
separate alpha for alpha values near and equal to 0.0 at single precision
floating point. Thus these symmetric conversions also augment associated alpha
to always maintain color information.
This is achieved by clamping the alpha used when computing the color
components when multiplying/dividing components between separate and
associated alpha to BABL_ALPHA_FLOOR and -BABL_ALPHA_FLOOR for values
near 0.0, the alpha value is copied unmodified between pixels; the main
improvement of this commit.
In the implementation BABL_ALPHA_FLOOR is 1/65536 = 0.00001526.. small
enough that it vanishing in rounding for 16bit integer alpha but large
enough to retain color data.
The following table illustrates what corresponding values are between the
two alpha encodings supported. We here usea BABL_ALPHA_FLOOR of 0.01 instead
of 0.00001526 to make it easier to see what happens.
GEGL lets each operation compute with it's preferred encoding - for some
operations like blurs this is associated alpha, for others like color
adjustments it is separate alpha, perhaps even in CIE Lab based encodings
rather than RGB. An earlier iteration of this approach was already in use in
babl making un-erase mode and similar features in GIMP-2.10 work correctly
after blurring, the previous implementation did not preserve the
alpha value.
Just the core of the implementation follows:
```
#define BABL_ALPHA_FLOOR_F (1.0f/65536.0f)
static inline float
babl_epsilon_for_zero_float (float value)
{
if (value <= BABL_ALPHA_FLOOR_F)
{
/* for performance one could directly retun BABL_ALPHA_FLOOR_F here
and dropping handling negative values consistently. */
if (value >= 0.0f)
return BABL_ALPHA_FLOOR_F;
else if (value >= -BABL_ALPHA_FLOOR_F)
return -BABL_ALPHA_FLOOR_F;
}
return value; /* most common case, return input value */
}
Øyvind Kolås [Tue, 28 May 2019 23:58:30 +0000 (01:58 +0200)]
babl: implement babl_space_get_rgb_luminance
This provides the factors often found as defines hard-coded for sRGB
with values that are adapted to the primaries of the RGB family of
pixel encodings for a given babl space.
projects / babl.git / log