s/nohalo1/templates.h replace hassign by withsign and cosmetic
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Nicolas Robidoux
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@ -2,11 +2,12 @@
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*
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* Hacked for vips by J. Cupitt, 20/1/09
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*
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* Rename as nohalo1 and move "restrict" support to configure, 16/3/09
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* Rename as nohalo1 and move "restrict" support to configure by
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* J. Cupitt, 16/3/09
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*
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* Tweaks by N. Robidoux and J. Cupitt 4-17/3/09
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*
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* Tweaks by N. Robidoux 25/5/09
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* Tweaks by N. Robidoux 25-28/5/09
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*/
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/*
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@ -39,8 +40,8 @@
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/*
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* 2009 (c) Nicolas Robidoux
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*
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* Nicolas thanks Geert Jordaens, John Cupitt, Minglun Gong, Øyvind
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* Kolås, Ralf Meyer and Sven Neumann for useful comments and code.
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* Nicolas thanks John Cupitt, Geert Jordaens, Øyvind Kolås, Ralf
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* Meyer, Minglun Gong, and Sven Neumann for useful comments and code.
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*
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* Nicolas Robidoux's research on Nohalo funded in part by an NSERC
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* (National Science and Engineering Research Council of Canada)
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@ -91,9 +92,9 @@
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* it. (Nohalo is not smoothing like, say, B-Spline
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* pseudo-interpolation.)
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*
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* ========================================================
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* Nohalo is co-monotone (this is why it's called "nohalo")
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* ========================================================
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* ==================================================================
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* Nohalo is co-monotone (this is why it's called "nohalo" = no halo)
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* ==================================================================
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*
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* What monotonicity more or less means here is that the resampled
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* value is in the range of the four closest input values. This
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@ -105,15 +106,21 @@
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* Note: If the abyss policy is an extrapolating one---for example,
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* linear or bilinear extrapolation---clamping is still unnecessary
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* unless one attempts to resample outside of the convex hull of the
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* input pixel positions. Consequence: the "corner" image size
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* convention does not require clamping when using linear
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* input pixel positions. Consequence: the usual "interpolatory" image
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* size convention (oft associated with "pixel center-based
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* coordinates") does not require clamping when using linear
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* extrapolation abyss policy when performing image resizing, but the
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* "center" one does, when upscaling, at locations very close to the
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* boundary. If computing values at locations outside of the convex
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* hull of the pixel locations of the input image, nearest neighbour
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* abyss policy is most likely better anyway, because linear
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* extrapolation produces "streaks" if positions far outside the
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* original image boundary are resampled.
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* usual "exact area" image size convention (oft associated with
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* "pixel corner-based coordinates) does require clamping at locations
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* very close to the boundary when upscaling. If computing values at
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* locations outside of the convex hull of the pixel center locations
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* of the input image, nearest neighbour abyss policy is most likely
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* better anyway, because linear extrapolation produces "streaks" if
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* positions far outside the original image boundary are sampled. Note
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* that the nearest neighbor abyss policy ("clamp" in GPU parlance) is
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* the most common one. Again, for this abyss policy, nohalo is
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* monotone through and through and no pixel value clamping is
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* necessary.
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*
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* ========================
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* Nohalo is a local method
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@ -189,7 +196,19 @@
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* used and the magnification factor is 2, that is, if the resampled
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* points sit exactly on the binary subdivided grid, then nohalo level
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* 1 gives the same result as as level=infinity, and consequently the
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* intensity surface can be treated as if smooth.)
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* intensity surface can be treated as if smooth.) Note that these
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* gradient discontinuities are nearly invisible when the
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* magnification ratio is modest.
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*
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* ============================
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* CONVENTIONS USED IN THE CODE
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* ============================
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*
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* This code uses the "center-based coordinate convention, for which,
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* the very first actual image pixel is understood to be located at
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* (0,0), and the last one at (N-1,M-1), where M is the number of
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* pixel rows of the input image, and N is its number of pixel
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* columns.
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*/
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#ifdef HAVE_CONFIG_H
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@ -552,7 +571,7 @@ nohalo1( const double uno_two,
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}
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NOHALO1_INTER( fptypes )
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NOHALO1_INTER( hassign )
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NOHALO1_INTER( withsign )
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NOHALO1_INTER( nosign )
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/* We need C linkage for this.
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@ -570,7 +589,7 @@ vips_interpolate_nohalo1_interpolate( VipsInterpolate* restrict interpolate,
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double absolute_y )
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{
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/*
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* VIPS versions of Nicolas's pixel addressing values.
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* Unit buffer pointer shifts:
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*/
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const int actual_bands = in->im->Bands;
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const int lskip = IM_REGION_LSKIP( in ) / IM_IMAGE_SIZEOF_ELEMENT( in->im );
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@ -622,7 +641,7 @@ vips_interpolate_nohalo1_interpolate( VipsInterpolate* restrict interpolate,
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break;
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case IM_BANDFMT_CHAR:
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CALL( signed char, hassign );
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CALL( signed char, withsign );
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break;
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case IM_BANDFMT_USHORT:
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@ -630,7 +649,7 @@ vips_interpolate_nohalo1_interpolate( VipsInterpolate* restrict interpolate,
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break;
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case IM_BANDFMT_SHORT:
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CALL( signed short, hassign );
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CALL( signed short, withsign );
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break;
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case IM_BANDFMT_UINT:
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@ -638,7 +657,7 @@ vips_interpolate_nohalo1_interpolate( VipsInterpolate* restrict interpolate,
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break;
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case IM_BANDFMT_INT:
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CALL( signed int, hassign );
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CALL( signed int, withsign );
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break;
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/* Complex images handled by doubling of bands, see above.
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@ -1,8 +1,10 @@
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/* snohalo (smooth nohalo) level 1 interpolator
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/* snohalo level 1 interpolator
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*
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* (smooth nohalo = nohalo with custom antialiasing blur)
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*
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* Tweaks by N. Robidoux and J. Cupitt 4-17/3/09
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*
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* Tweaks by N. Robidoux 25/5/09
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* Tweaks by N. Robidoux 25-28/5/09
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*/
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/*
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@ -485,7 +487,7 @@ snohalo1( const double blur,
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}
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SNOHALO1_INTER( fptypes )
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SNOHALO1_INTER( hassign )
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SNOHALO1_INTER( withsign )
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SNOHALO1_INTER( nosign )
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/* We need C linkage for this.
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@ -558,7 +560,7 @@ vips_interpolate_snohalo1_interpolate( VipsInterpolate* restrict interpolate,
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break;
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case IM_BANDFMT_CHAR:
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CALL( signed char, hassign );
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CALL( signed char, withsign );
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break;
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case IM_BANDFMT_USHORT:
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@ -566,7 +568,7 @@ vips_interpolate_snohalo1_interpolate( VipsInterpolate* restrict interpolate,
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break;
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case IM_BANDFMT_SHORT:
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CALL( signed short, hassign );
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CALL( signed short, withsign );
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break;
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case IM_BANDFMT_UINT:
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@ -574,7 +576,7 @@ vips_interpolate_snohalo1_interpolate( VipsInterpolate* restrict interpolate,
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break;
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case IM_BANDFMT_INT:
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CALL( signed int, hassign );
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CALL( signed int, withsign );
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break;
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/* Complex images handled by doubling of bands, see above.
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@ -68,7 +68,7 @@ bilinear_fptypes(
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/* Interpolate for signed integer types.
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*/
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template <typename T> static T inline
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bilinear_hassign(
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bilinear_withsign(
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const double w_times_z,
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const double x_times_z,
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const double w_times_y,
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