+2010-09-14 6.6.4-2 Anthony Thyssen <A.Thyssen@griffith...>
+ * Switch default resize filters to using the faster SincPolynomial
+ filter by default internally. However 'Sinc' will stil use the
+ Trigonometric function, and can be used to assign the trig version
+ of Sinc() to filters using the filter expert options.
+ * Removed the default filter for 'distort' was found to be a very
+ blurry inaccurate filter function. It was removed and replaced with
+ a correct Gussian filter (as used by resize)
+ * Added a switch so that "-interpolate filter" will force the use of
+ a cylindrical filter for ALL pixels in distorted images. That is you can
+ use that swicth to use a cylindrical filter even for images that are
+ being enlarged by the distortion. IT is alightly slower though.
+ However EWA is still currently using a fixed 2.0 sampling radius.
+ This switch complements the use of "-filter point" which turns of EWA
+ filters in favor of interpolation for all pixels in a distiorted image.
+ BOTH switched should not be used together.
+ * A bug in the support radius of the EWA resampling function was found,
+ now that correctly defined resize filters are being used. Suddenly Normal
+ Gaussian distortions are not so blurry, and tests with distortions of
+ the 'Rings' image show extremely good and clear results, with only minimal
+ blurring. The filter 'blur' expert option can be used to adjust this
+ further.
+
+ The above represents a major impovment forward in the quality of the image
+ distortion operator.
+
2010-09-13 6.6.4-2 Cristy <quetzlzacatenango@image...>
* Don't negate the geometry offset for the -extent option.
#if 0
/* Direct conversions of derivatives to elliptical coefficients
No scaling will result in F == 1.0 and a unit circle.
+ However if the ellipse becomes very small (magnification) or
+ very long and thin, the ellipse may miss all source pixels!
*/
A = dvx*dvx+dvy*dvy;
B = (dux*dvx+duy*dvy)*-2.0;
C = dux*dux+duy*duy;
F = dux*dvy+duy*dvx;
- F *= F;
+ F *= F; /* square it */
#define F_UNITY 1.0
#else
/* This Paul Heckbert's recomended "Higher Quality EWA" formula, from page
- 60 in his thesis, which adds a unit circle to the elliptical area so are
+ 60 in his thesis, which adds a unit circle to the elliptical area so as
to do both Reconstruction and Prefiltering of the pixels in the
- resampling. It also means it is likely to have at least 4 pixels within
- the area of the ellipse, for weighted averaging.
- No scaling will result if F == 4.0 and a circle of radius 2.0
+ resampling. It also means it is always likely to have at least 4 pixels
+ within the area of the ellipse, for weighted averaging. No scaling will
+ result if F == 4.0 and a circle of radius 2.0, and F smaller than this
+ means magnification is being used.
*/
A = dvx*dvx+dvy*dvy+1;
B = (dux*dvx+duy*dvy)*-2.0;
}
#endif
- /* Is default elliptical area, too small? Image being magnified?
- Switch to doing pure 'point' interpolation of the pixel.
- That is turn off EWA Resampling.
+ /* Is default elliptical area, too small? Then the image is being magnified.
+ Switch to using a orthogonal interpolation method,
+ unless 'filter' interpolation was specifically requested.
*/
- if ( F <= F_UNITY ) {
+ if ( F <= F_UNITY && resample_filter->interpolate != FilterInterpolatePixel ) {
resample_filter->do_interpolate = MagickTrue;
return;
}
/* If F is impossibly large, we may as well not bother doing any
- * form of resampling, as you risk an infinite resampled area.
+ form of resampling, as you risk an near infinite resampled area.
+ In this case some alturnative means of pixel sampling, such as
+ the average of the whole image is needed to get a reasonable result.
*/
if ( F > MagickHuge ) {
resample_filter->limit_reached = MagickTrue;
/* The size of the area of the parallelogram we will be sampling */
area = 4 * resample_filter->sqrtA * resample_filter->sqrtU;
- /* Absolute limit on the area to be resampled
+ /* Absolute limit on the area to be resampled.
* This limit needs more work, as it gets too slow for
* larger images involved with tiled views of the horizon. */
if ( area > 20.0*resample_filter->image_area ) {
return;
}
- /* Scale ellipse formula to directly fit the Filter Lookup Table */
+ /* Scale ellipse formula to directly index the Filter Lookup Table */
{ register double scale;
- scale = (double)WLUT_WIDTH/F;
+ scale = (double)WLUT_WIDTH/(F*4); /* 4 = cache_support^2 */
resample_filter->A = A*scale;
resample_filter->B = B*scale;
resample_filter->C = C*scale;
Future: Direct use of the resize filters in "resize.c" to set the lookup
table, based on the filters working support window.
*/
- r_scale = sqrt(1.0/(double)(WLUT_WIDTH*blur));
+ r_scale = sqrt(1.0/(double)WLUT_WIDTH);
r_scale *= 2; /* for 2 pixel radius of Improved Elliptical Formula */
- switch ( filter ) {
+ switch ( resample_filter->filter ) {
case PointFilter:
/* This equivelent to turning off the EWA algroithm.
Only Interpolated lookup will be used. */
break;
+ case UndefinedFilter:
+ resample_filter->filter = GaussianFilter;
+ /* FALL-THRU */
default:
/*
Fill the LUT with a 1D resize filter function
But make the Sinc/Bessel tapered window 2.0
I also normalize the result so the filter is 1.0
*/
- resize_filter = AcquireResizeFilter(resample_filter->image,filter,
- (MagickRealType)1.0,MagickTrue,resample_filter->exception);
+ resize_filter = AcquireResizeFilter(resample_filter->image,
+ resample_filter->filter,blur,MagickTrue,resample_filter->exception);
if (resize_filter != (ResizeFilter *) NULL) {
+#if 0
+ /* At this time the filter support is completely ignored! */
resample_filter->support = GetResizeFilterSupport(resize_filter);
resample_filter->support /= blur; /* taken into account above */
resample_filter->support *= resample_filter->support;
resample_filter->support *= (double)WLUT_WIDTH/4;
if ( resample_filter->support >= (double)WLUT_WIDTH )
- resample_filter->support = (double)WLUT_WIDTH; /* hack */
+ resample_filter->support = (double)WLUT_WIDTH; /* not used yet */
+#endif
for(Q=0; Q<WLUT_WIDTH; Q++)
- if ( (double) Q < resample_filter->support )
+ //if ( (double) Q < resample_filter->support )
resample_filter->filter_lut[Q] = (double)
GetResizeFilterWeight(resize_filter,sqrt((double)Q)*r_scale);
- else
- resample_filter->filter_lut[Q] = 0.0;
+ //else
+ // resample_filter->filter_lut[Q] = 0.0;
resize_filter = DestroyResizeFilter(resize_filter);
break;
}
ModuleError, "UnableToSetFilteringValue",
"Fall back to default EWA gaussian filter");
}
- /* FALLTHRU - on exception */
+#if 0
/*case GaussianFilter:*/
case UndefinedFilter:
/*
and ALPHA = -4.0*ln(2.0) ==> -2.77258872223978123767
However the table is of length 1024, and equates to a radius of 2px
thus needs to be scaled by ALPHA*4/1024 and any blur factor squared
+
+ This is now known to be wrong -- very wrong!
*/
/*r_scale = -2.77258872223978123767*4/WLUT_WIDTH/blur/blur;*/
r_scale = -2.77258872223978123767/(WLUT_WIDTH*blur*blur);
resample_filter->filter_lut[Q] = exp((double)Q*r_scale);
resample_filter->support = WLUT_WIDTH;
break;
+#endif
}
if (GetImageArtifact(resample_filter->image,"resample:verbose")
!= (const char *) NULL)
- /* Debug output of the filter weighting LUT
- Gnuplot the LUT with hoizontal adjusted to 'r' using...
- plot [0:2][-.2:1] "lut.dat" using (sqrt($0/1024)*2):1 with lines
- The filter values is normalized for comparision
- */
- printf("# Resampling Filter LUT (%d values)\n", WLUT_WIDTH);
- printf("#\n");
- printf("# Plot using the gnuplot command\n");
- printf("# plot [0:2][-.2:1] \"lut.dat\" using ");
- printf("sqrt($0/%d)*2):1 with lines\n", WLUT_WIDTH);
- printf("#\n");
- for(Q=0; Q<WLUT_WIDTH; Q++)
- printf("%lf\n", resample_filter->filter_lut[Q]
- /resample_filter->filter_lut[0] );
+ {
+ /* Debug output of the filter weighting LUT
+ Gnuplot the LUT with hoizontal adjusted to 'r' using...
+ plot [0:2][-.2:1] "lut.dat" using (sqrt($0/1024)*2):1 with lines
+ The filter values is normalized for comparision
+ */
+ printf("# Resampling Filter LUT (%d values)\n", WLUT_WIDTH);
+ printf("#\n");
+ printf("# Plot using the gnuplot command\n");
+ printf("# plot [0:2][-.2:1] \"lut.dat\" ");
+ printf( "using (sqrt($0/%d)*2):1 with lines\n", WLUT_WIDTH);
+ printf("#\n");
+ for(Q=0; Q<WLUT_WIDTH; Q++)
+ printf("%lf\n", resample_filter->filter_lut[Q]
+ /resample_filter->filter_lut[0] );
+ }
return;
}
\f
projects / imagemagick / commitdiff