im_scaleps() is a class

actually an option to vips_scale(), with a param for the exponent as
well

ChangeLog

@@ -3,7 +3,8 @@
 - turn off caching for im_copy()/vips_copy(), we use copy to stop sharing, and
 it's cheap so caching doesn't help anyway
 - auto rshift down to 8 bits on save, if necessary
-- im_gaussnoise(), im_copy_file(), im_grid(), im_scale() redone as classes
+- im_gaussnoise(), im_copy_file(), im_grid(), im_scale(), im_scaleps() 
+  redone as classes
 - add --angle option to dzsave
 
 14/5/13 started 7.32.4

libvips/conversion/Makefile.am

@@ -30,7 +30,6 @@ libconversion_la_SOURCES = \
 	im_msb.c \
 	grid.c \
 	scale.c \
-	im_scaleps.c \
 	im_subsample.c \
 	im_system.c \
 	im_system_image.c \

libvips/conversion/im_scaleps.c

@@ -1,100 +0,0 @@
-/* im_scaleps
- *
- * Copyright: 1990, N. Dessipris.
- *
- * Author: Nicos Dessipris
- * Written on: 02/05/1990
- * Modified on: 14/03/1991
- * 15/6/93 J.Cupitt
- *	- externs fixed
- *	- includes fixed
- * 13/2/95 JC
- *	- ANSIfied
- *	- cleaned up
- * 11/7/02 JC
- *	- rewritten ... got rid of the stuff for handling -ves, never used
- *	  (and was broken anyway)
- * 1/2/10
- * 	- gtkdoc
- */
-
-/*
-
-    This file is part of VIPS.
-    
-    VIPS is free software; you can redistribute it and/or modify
-    it under the terms of the GNU Lesser General Public License as published by
-    the Free Software Foundation; either version 2 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU Lesser General Public License for more details.
-
-    You should have received a copy of the GNU Lesser General Public License
-    along with this program; if not, write to the Free Software
-    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-    02110-1301  USA
-
- */
-
-/*
-
-    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
-
- */
-
-#ifdef HAVE_CONFIG_H
-#include <config.h>
-#endif /*HAVE_CONFIG_H*/
-#include <vips/intl.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <math.h>
-
-#include <vips/vips.h>
-
-/**
- * im_scaleps:
- * @in: input image
- * @out: output image
- *
- * Scale a power spectrum. Transform with log10(1.0 + pow(x, 0.25)) + .5, 
- * then scale so max == 255.
- *
- * See also: im_scale().
- *
- * Returns: 0 on success, -1 on error
- */
-int 
-im_scaleps( IMAGE *in, IMAGE *out )
-{
-	IMAGE *t[4];
-	double mx;
-	double scale;
-
-	if( im_open_local_array( out, t, 4, "im_scaleps-1", "p" ) || 
-		im_max( in, &mx ) )
-		return( -1 );
-
-	if( mx <= 0.0 ) 
-		/* Range of zero: just return black.
-		 */
-		return( im_black( out, in->Xsize, in->Ysize, in->Bands ) );
-
-	scale = 255.0 / log10( 1.0 + pow( mx, .25 ) );
-
-	/* Transform!
-	 */
-	if( im_powtra( in, t[0], 0.25 ) ||
-		im_lintra( 1.0, t[0], 1.0, t[1] ) ||
-		im_log10tra( t[1], t[2] ) ||
-		im_lintra( scale, t[2], 0.0, t[3] ) ||
-		im_clip2fmt( t[3], out, IM_BANDFMT_UCHAR ) )
-		return( -1 );
-
-	return( 0 );
-}
-

libvips/conversion/scale.c

@@ -17,6 +17,7 @@
  * 	- gtkdoc
  * 30/5/13
  * 	- redo as a class
+ * 	- add log scale and exponent as an option
  */
 
 /*
@@ -63,6 +64,9 @@ typedef struct _VipsScale {
 
 	VipsImage *in;
 
+	gboolean log;
+	double exp;
+
 } VipsScale;
 
 typedef VipsConversionClass VipsScaleClass;
@@ -98,6 +102,17 @@ vips_scale_build( VipsObject *object )
 			vips_image_write( t[1], conversion->out ) )
 			return( -1 );
 	}
+	else if( scale->log ) { 
+		double f = 255.0 / log10( 1.0 + pow( mx, scale->exp ) );
+
+		if( vips_pow_const1( scale->in, &t[2], scale->exp, NULL ) ||
+			vips_linear1( t[2], &t[3], 1.0, 1.0, NULL ) ||
+			vips_log10( t[3], &t[4], NULL ) ||
+			vips_linear1( t[4], &t[5], f, 0.0, NULL ) ||
+			vips_cast( t[5], &t[6], VIPS_FORMAT_UCHAR, NULL ) ||
+			vips_image_write( t[6], conversion->out ) )
+			return( -1 );
+	}
 	else {
 		double f = 255.0 / (mx - mn);
 		double a = -(mn * f);
@@ -130,11 +145,26 @@ vips_scale_class_init( VipsScaleClass *class )
 		VIPS_ARGUMENT_REQUIRED_INPUT,
 		G_STRUCT_OFFSET( VipsScale, in ) );
 
+	VIPS_ARG_BOOL( class, "log", 3, 
+		_( "Log" ), 
+		_( "Log scale" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsScale, log ),
+		FALSE );
+
+	VIPS_ARG_DOUBLE( class, "exp", 3, 
+		_( "Exponent" ), 
+		_( "Exponent for log scale" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsScale, exp ),
+		0.00001, 10000, 0.25 );
+
 }
 
 static void
 vips_scale_init( VipsScale *scale )
 {
+	scale->exp = 0.25;
 }
 
 /**
@@ -143,10 +173,18 @@ vips_scale_init( VipsScale *scale )
  * @out: output image
  * @...: %NULL-terminated list of optional named arguments
  *
+ * Optional arguments:
+ *
+ * @log: log scale pixels
+ * @exp: exponent for log scale
+ *
  * Search the image for the maximum and minimum value, then return the image
  * as unsigned 8-bit, scaled so that the maximum value is 255 and the
  * minimum is zero.
  *
+ * If @log is set, transform with log10(1.0 + pow(x, @exp)) + .5, 
+ * then scale so max == 255. By default, @exp is 0.25.
+ *
  * See also: vips_cast().
  *
  * Returns: 0 on success, -1 on error

libvips/deprecated/vips7compat.c

@@ -1527,6 +1527,22 @@ im_scale( VipsImage *in, VipsImage *out )
 	return( 0 );
 }
 
+int 
+im_scaleps( VipsImage *in, VipsImage *out )
+{
+	VipsImage *t;
+
+	if( vips_scale( in, &t, "log", TRUE, NULL ) )
+		return( -1 );
+	if( vips_image_write( t, out ) ) {
+		g_object_unref( t );
+		return( -1 );
+	}
+	g_object_unref( t );
+
+	return( 0 );
+}
+
 static int
 vips__math( VipsImage *in, VipsImage *out, VipsOperationMath math )
 {

libvips/include/vips/conversion.h

@@ -258,8 +258,6 @@ int vips_flatten( VipsImage *in, VipsImage **out, ... )
 int im_msb( VipsImage *in, VipsImage *out );
 int im_msb_band( VipsImage *in, VipsImage *out, int band );
 
-int im_scaleps( VipsImage *in, VipsImage *out );
-
 int im_falsecolour( VipsImage *in, VipsImage *out );
 
 int im_text( VipsImage *out, const char *text, const char *font,

libvips/include/vips/vips7compat.h

@@ -712,6 +712,7 @@ int im_black( VipsImage *out, int x, int y, int bands );
 int im_gaussnoise( VipsImage *out, int x, int y, double mean, double sigma );
 int im_grid( VipsImage *in, VipsImage *out, int tile_height, int across, int down );
 int im_scale( VipsImage *in, VipsImage *out );
+int im_scaleps( VipsImage *in, VipsImage *out );
 
 int im_c2amph( VipsImage *in, VipsImage *out );
 int im_c2rect( VipsImage *in, VipsImage *out );

po/POTFILES.in

@@ -75,7 +75,6 @@ libvips/conversion/replicate.c
 libvips/conversion/join.c
 libvips/conversion/im_text.c
 libvips/conversion/conver_dispatch.c
-libvips/conversion/im_scaleps.c
 libvips/conversion/im_wrap.c
 libvips/conversion/insert.c
 libvips/conversion/tilecache.c