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adaptmap.c
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adaptmap.c
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/*====================================================================*
- Copyright (C) 2001 Leptonica. All rights reserved.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
- 1. Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
- 2. Redistributions in binary form must reproduce the above
- copyright notice, this list of conditions and the following
- disclaimer in the documentation and/or other materials
- provided with the distribution.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ANY
- CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
- NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*====================================================================*/
/*!
* \file adaptmap.c
* <pre>
*
* -------------------------------------------------------------------
*
* Image binarization algorithms are found in:
* grayquant.c: standard, simple, general grayscale quantization
* adaptmap.c: local adaptive; mostly gray-to-gray in preparation
* for binarization
* binarize.c: special binarization methods, locally adaptive.
*
* -------------------------------------------------------------------
*
* Clean background to white using background normalization
* PIX *pixCleanBackgroundToWhite()
*
* Adaptive background normalization (top-level functions)
* PIX *pixBackgroundNormSimple() 8 and 32 bpp
* PIX *pixBackgroundNorm() 8 and 32 bpp
* PIX *pixBackgroundNormMorph() 8 and 32 bpp
*
* Arrays of inverted background values for normalization (16 bpp)
* l_int32 pixBackgroundNormGrayArray() 8 bpp input
* l_int32 pixBackgroundNormRGBArrays() 32 bpp input
* l_int32 pixBackgroundNormGrayArrayMorph() 8 bpp input
* l_int32 pixBackgroundNormRGBArraysMorph() 32 bpp input
*
* Measurement of local background
* l_int32 pixGetBackgroundGrayMap() 8 bpp
* l_int32 pixGetBackgroundRGBMap() 32 bpp
* l_int32 pixGetBackgroundGrayMapMorph() 8 bpp
* l_int32 pixGetBackgroundRGBMapMorph() 32 bpp
* l_int32 pixFillMapHoles()
* PIX *pixExtendByReplication() 8 bpp
* l_int32 pixSmoothConnectedRegions() 8 bpp
*
* Measurement of local foreground
* l_int32 pixGetForegroundGrayMap() 8 bpp
*
* Generate inverted background map for each component
* PIX *pixGetInvBackgroundMap() 16 bpp
*
* Apply inverse background map to image
* PIX *pixApplyInvBackgroundGrayMap() 8 bpp
* PIX *pixApplyInvBackgroundRGBMap() 32 bpp
*
* Apply variable map
* PIX *pixApplyVariableGrayMap() 8 bpp
*
* Non-adaptive (global) mapping
* PIX *pixGlobalNormRGB() 32 bpp or cmapped
* PIX *pixGlobalNormNoSatRGB() 32 bpp
*
* Adaptive threshold spread normalization
* l_int32 pixThresholdSpreadNorm() 8 bpp
*
* Adaptive background normalization (flexible adaptaption)
* PIX *pixBackgroundNormFlex() 8 bpp
*
* Adaptive contrast normalization
* PIX *pixContrastNorm() 8 bpp
* static l_int32 pixMinMaxTiles()
* static l_int32 pixSetLowContrast()
* static PIX *pixLinearTRCTiled()
* static l_int32 *iaaGetLinearTRC()
*
* Background normalization is done by generating a reduced map (or set
* of maps) representing the estimated background value of the
* input image, and using this to shift the pixel values so that
* this background value is set to some constant value.
*
* Specifically, normalization has 3 steps:
* (1) Generate a background map at a reduced scale.
* (2) Make the array of inverted background values by inverting
* the map. The result is an array of local multiplicative factors.
* (3) Apply this inverse background map to the image
*
* The inverse background arrays can be generated in two different ways here:
* (1) Remove the 'foreground' pixels and average over the remaining
* pixels in each tile. Propagate values into tiles where
* values have not been assigned, either because there was not
* enough background in the tile or because the tile is covered
* by a foreground region described by an image mask.
* After the background map is made, the inverse map is generated by
* smoothing over some number of adjacent tiles
* (block convolution) and then inverting.
* (2) Remove the foreground pixels using a morphological closing
* on a subsampled version of the image. Propagate values
* into pixels covered by an optional image mask. Invert the
* background map without preconditioning by convolutional smoothing.
*
* Other methods for adaptively normalizing the image are also given here.
*
* (1) pixThresholdSpreadNorm() computes a local threshold over the image
* and normalizes the input pixel values so that this computed threshold
* is a constant across the entire image.
*
* (2) pixContrastNorm() computes and applies a local TRC so that the
* local dynamic range is expanded to the full 8 bits, where the
* darkest pixels are mapped to 0 and the lightest to 255. This is
* useful for improving the appearance of pages with very light
* foreground or very dark background, and where the local TRC
* function doesn't change rapidly with position.
* </pre>
*/
#ifdef HAVE_CONFIG_H
#include <config_auto.h>
#endif /* HAVE_CONFIG_H */
#include "allheaders.h"
/* Default input parameters for pixBackgroundNormSimple()
* Notes:
* (1) mincount must never exceed the tile area (width * height)
* (2) bgval must be sufficiently below 255 to avoid accidental
* saturation; otherwise it should be large to avoid
* shrinking the dynamic range
* (3) results should otherwise not be sensitive to these values
*/
static const l_int32 DefaultTileWidth = 10; /*!< default tile width */
static const l_int32 DefaultTileHeight = 15; /*!< default tile height */
static const l_int32 DefaultFgThreshold = 60; /*!< default fg threshold */
static const l_int32 DefaultMinCount = 40; /*!< default minimum count */
static const l_int32 DefaultBgVal = 200; /*!< default bg value */
static const l_int32 DefaultXSmoothSize = 2; /*!< default x smooth size */
static const l_int32 DefaultYSmoothSize = 1; /*!< default y smooth size */
static l_int32 pixMinMaxTiles(PIX *pixs, l_int32 sx, l_int32 sy,
l_int32 mindiff, l_int32 smoothx, l_int32 smoothy,
PIX **ppixmin, PIX **ppixmax);
static l_int32 pixSetLowContrast(PIX *pixs1, PIX *pixs2, l_int32 mindiff);
static PIX *pixLinearTRCTiled(PIX *pixd, PIX *pixs, l_int32 sx, l_int32 sy,
PIX *pixmin, PIX *pixmax);
static l_int32 *iaaGetLinearTRC(l_int32 **iaa, l_int32 diff);
#ifndef NO_CONSOLE_IO
#define DEBUG_GLOBAL 0 /*!< set to 1 to debug pixGlobalNormNoSatRGB() */
#endif /* ~NO_CONSOLE_IO */
/*------------------------------------------------------------------*
* Clean background to white using background normalization *
*------------------------------------------------------------------*/
/*!
* \brief pixCleanBackgroundToWhite()
*
* \param[in] pixs 8 bpp grayscale or 32 bpp rgb
* \param[in] pixim [optional] 1 bpp 'image' mask; can be null
* \param[in] pixg [optional] 8 bpp grayscale version; can be null
* \param[in] gamma gamma correction; must be > 0.0; typically ~1.0
* \param[in] blackval dark value to set to black (0)
* \param[in] whiteval light value to set to white (255)
* \return pixd 8 bpp or 32 bpp rgb, or NULL on error
*
* <pre>
* Notes:
* (1) This is a simplified interface for cleaning an image.
* For comparison, see pixAdaptThresholdToBinaryGen().
* (2) The suggested default values for the input parameters are:
* gamma: 1.0 (reduce this to increase the contrast; e.g.,
* for light text)
* blackval 70 (a bit more than 60)
* whiteval 190 (a bit less than 200)
* (3) Note: the whiteval must not exceed 200, which is the value
* that the background is set to in pixBackgroundNormSimple().
* </pre>
*/
PIX *
pixCleanBackgroundToWhite(PIX *pixs,
PIX *pixim,
PIX *pixg,
l_float32 gamma,
l_int32 blackval,
l_int32 whiteval)
{
l_int32 d;
PIX *pixd;
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
d = pixGetDepth(pixs);
if (d != 8 && d != 32)
return (PIX *)ERROR_PTR("depth not 8 or 32", __func__, NULL);
if (whiteval > 200) {
L_WARNING("white value %d must not exceed 200; reset to 190",
__func__, whiteval);
whiteval = 190;
}
pixd = pixBackgroundNormSimple(pixs, pixim, pixg);
if (!pixd)
return (PIX *)ERROR_PTR("background norm failedd", __func__, NULL);
pixGammaTRC(pixd, pixd, gamma, blackval, whiteval);
return pixd;
}
/*------------------------------------------------------------------*
* Adaptive background normalization *
*------------------------------------------------------------------*/
/*!
* \brief pixBackgroundNormSimple()
*
* \param[in] pixs 8 bpp grayscale or 32 bpp rgb
* \param[in] pixim [optional] 1 bpp 'image' mask; can be null
* \param[in] pixg [optional] 8 bpp grayscale version; can be null
* \return pixd 8 bpp or 32 bpp rgb, or NULL on error
*
* <pre>
* Notes:
* (1) This is a simplified interface to pixBackgroundNorm(),
* where seven parameters are defaulted.
* (2) The input image is either grayscale or rgb.
* (3) See pixBackgroundNorm() for usage and function.
* </pre>
*/
PIX *
pixBackgroundNormSimple(PIX *pixs,
PIX *pixim,
PIX *pixg)
{
return pixBackgroundNorm(pixs, pixim, pixg,
DefaultTileWidth, DefaultTileHeight,
DefaultFgThreshold, DefaultMinCount,
DefaultBgVal, DefaultXSmoothSize,
DefaultYSmoothSize);
}
/*!
* \brief pixBackgroundNorm()
*
* \param[in] pixs 8 bpp grayscale or 32 bpp rgb
* \param[in] pixim [optional] 1 bpp 'image' mask; can be null
* \param[in] pixg [optional] 8 bpp grayscale version; can be null
* \param[in] sx, sy tile size in pixels
* \param[in] thresh threshold for determining foreground
* \param[in] mincount min threshold on counts in a tile
* \param[in] bgval target bg val; typ. > 128
* \param[in] smoothx half-width of block convolution kernel width
* \param[in] smoothy half-width of block convolution kernel height
* \return pixd 8 bpp or 32 bpp rgb, or NULL on error
*
* <pre>
* Notes:
* (1) This is a top-level interface for normalizing the image intensity
* by mapping the image so that the background is near the input
* value %bgval.
* (2) The input image is either grayscale or rgb.
* (3) For each component in the input image, the background value
* in each tile is estimated using the values in the tile that
* are not part of the foreground, where the foreground is
* determined by %thresh.
* (4) An optional binary mask can be specified, with the foreground
* pixels typically over image regions. The resulting background
* map values will be determined by surrounding pixels that are
* not under the mask foreground. The origin (0,0) of this mask
* is assumed to be aligned with the origin of the input image.
* This binary mask must not fully cover pixs, because then there
* will be no pixels in the input image available to compute
* the background.
* (5) An optional grayscale version of the input pixs can be supplied.
* The only reason to do this is if the input is RGB and this
* grayscale version can be used elsewhere. If the input is RGB
* and this is not supplied, it is made internally using only
* the green component, and destroyed after use.
* (6) The dimensions of the pixel tile (%sx, %sy) give the amount by
* by which the map is reduced in size from the input image.
* (7) The input image is binarized using %thresh, in order to
* locate the foreground components. If this is set too low,
* some actual foreground may be used to determine the maps;
* if set too high, there may not be enough background
* to determine the map values accurately. Typically, it is
* better to err by setting the threshold too high.
* (8) A %mincount threshold is a minimum count of pixels in a
* tile for which a background reading is made, in order for that
* pixel in the map to be valid. This number should perhaps be
* at least 1/3 the size of the tile.
* (9) A %bgval target background value for the normalized image. This
* should be at least 128. If set too close to 255, some
* clipping will occur in the result. It is recommended to use
* %bgval = 200.
* (10) Two factors, %smoothx and %smoothy, are input for smoothing
* the map. Each low-pass filter kernel dimension is
* is 2 * (smoothing factor) + 1, so a
* value of 0 means no smoothing. A value of 1 or 2 is recommended.
* (11) See pixCleanBackgroundToWhite(). The recommended value for %bgval
* is 200. As done there, pixBackgroundNorm() is typically followed
* by pixGammaTRC(), where the maxval must not not exceed %bgval.
* </pre>
*/
PIX *
pixBackgroundNorm(PIX *pixs,
PIX *pixim,
PIX *pixg,
l_int32 sx,
l_int32 sy,
l_int32 thresh,
l_int32 mincount,
l_int32 bgval,
l_int32 smoothx,
l_int32 smoothy)
{
l_int32 d, allfg;
PIX *pixm, *pixmi, *pixd;
PIX *pixmr, *pixmg, *pixmb, *pixmri, *pixmgi, *pixmbi;
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
d = pixGetDepth(pixs);
if (d != 8 && d != 32)
return (PIX *)ERROR_PTR("pixs not 8 or 32 bpp", __func__, NULL);
if (sx < 4 || sy < 4)
return (PIX *)ERROR_PTR("sx and sy must be >= 4", __func__, NULL);
if (mincount > sx * sy) {
L_WARNING("mincount too large for tile size\n", __func__);
mincount = (sx * sy) / 3;
}
/* If pixim exists, verify that it is not all foreground. */
if (pixim) {
pixInvert(pixim, pixim);
pixZero(pixim, &allfg);
pixInvert(pixim, pixim);
if (allfg)
return (PIX *)ERROR_PTR("pixim all foreground", __func__, NULL);
}
pixd = NULL;
if (d == 8) {
pixm = NULL;
pixGetBackgroundGrayMap(pixs, pixim, sx, sy, thresh, mincount, &pixm);
if (!pixm) {
L_WARNING("map not made; return a copy of the source\n", __func__);
return pixCopy(NULL, pixs);
}
pixmi = pixGetInvBackgroundMap(pixm, bgval, smoothx, smoothy);
if (!pixmi) {
L_WARNING("pixmi not made; return a copy of source\n", __func__);
pixDestroy(&pixm);
return pixCopy(NULL, pixs);
} else {
pixd = pixApplyInvBackgroundGrayMap(pixs, pixmi, sx, sy);
}
pixDestroy(&pixm);
pixDestroy(&pixmi);
}
else {
pixmr = pixmg = pixmb = NULL;
pixGetBackgroundRGBMap(pixs, pixim, pixg, sx, sy, thresh,
mincount, &pixmr, &pixmg, &pixmb);
if (!pixmr || !pixmg || !pixmb) {
pixDestroy(&pixmr);
pixDestroy(&pixmg);
pixDestroy(&pixmb);
L_WARNING("map not made; return a copy of the source\n", __func__);
return pixCopy(NULL, pixs);
}
pixmri = pixGetInvBackgroundMap(pixmr, bgval, smoothx, smoothy);
pixmgi = pixGetInvBackgroundMap(pixmg, bgval, smoothx, smoothy);
pixmbi = pixGetInvBackgroundMap(pixmb, bgval, smoothx, smoothy);
if (!pixmri || !pixmgi || !pixmbi) {
L_WARNING("not all pixm*i are made; return src copy\n", __func__);
pixd = pixCopy(NULL, pixs);
} else {
pixd = pixApplyInvBackgroundRGBMap(pixs, pixmri, pixmgi, pixmbi,
sx, sy);
}
pixDestroy(&pixmr);
pixDestroy(&pixmg);
pixDestroy(&pixmb);
pixDestroy(&pixmri);
pixDestroy(&pixmgi);
pixDestroy(&pixmbi);
}
if (!pixd)
ERROR_PTR("pixd not made", __func__, NULL);
pixCopyResolution(pixd, pixs);
return pixd;
}
/*!
* \brief pixBackgroundNormMorph()
*
* \param[in] pixs 8 bpp grayscale or 32 bpp rgb
* \param[in] pixim [optional] 1 bpp 'image' mask; can be null
* \param[in] reduction at which morph closings are done; between 2 and 16
* \param[in] size of square Sel for the closing; use an odd number
* \param[in] bgval target bg val; typ. > 128
* \return pixd 8 bpp, or NULL on error
*
* <pre>
* Notes:
* (1) This is a top-level interface for normalizing the image intensity
* by mapping the image so that the background is near the input
* value 'bgval'.
* (2) The input image is either grayscale or rgb.
* (3) For each component in the input image, the background value
* is estimated using a grayscale closing; hence the 'Morph'
* in the function name.
* (4) An optional binary mask can be specified, with the foreground
* pixels typically over image regions. The resulting background
* map values will be determined by surrounding pixels that are
* not under the mask foreground. The origin (0,0) of this mask
* is assumed to be aligned with the origin of the input image.
* This binary mask must not fully cover pixs, because then there
* will be no pixels in the input image available to compute
* the background.
* (5) The map is computed at reduced size (given by 'reduction')
* from the input pixs and optional pixim. At this scale,
* pixs is closed to remove the background, using a square Sel
* of odd dimension. The product of reduction * size should be
* large enough to remove most of the text foreground.
* (6) No convolutional smoothing needs to be done on the map before
* inverting it.
* (7) A 'bgval' target background value for the normalized image. This
* should be at least 128. If set too close to 255, some
* clipping will occur in the result.
* </pre>
*/
PIX *
pixBackgroundNormMorph(PIX *pixs,
PIX *pixim,
l_int32 reduction,
l_int32 size,
l_int32 bgval)
{
l_int32 d, allfg;
PIX *pixm, *pixmi, *pixd;
PIX *pixmr, *pixmg, *pixmb, *pixmri, *pixmgi, *pixmbi;
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
d = pixGetDepth(pixs);
if (d != 8 && d != 32)
return (PIX *)ERROR_PTR("pixs not 8 or 32 bpp", __func__, NULL);
if (reduction < 2 || reduction > 16)
return (PIX *)ERROR_PTR("reduction must be between 2 and 16",
__func__, NULL);
/* If pixim exists, verify that it is not all foreground. */
if (pixim) {
pixInvert(pixim, pixim);
pixZero(pixim, &allfg);
pixInvert(pixim, pixim);
if (allfg)
return (PIX *)ERROR_PTR("pixim all foreground", __func__, NULL);
}
pixd = NULL;
if (d == 8) {
pixGetBackgroundGrayMapMorph(pixs, pixim, reduction, size, &pixm);
if (!pixm)
return (PIX *)ERROR_PTR("pixm not made", __func__, NULL);
pixmi = pixGetInvBackgroundMap(pixm, bgval, 0, 0);
if (!pixmi)
ERROR_PTR("pixmi not made", __func__, NULL);
else
pixd = pixApplyInvBackgroundGrayMap(pixs, pixmi,
reduction, reduction);
pixDestroy(&pixm);
pixDestroy(&pixmi);
}
else { /* d == 32 */
pixmr = pixmg = pixmb = NULL;
pixGetBackgroundRGBMapMorph(pixs, pixim, reduction, size,
&pixmr, &pixmg, &pixmb);
if (!pixmr || !pixmg || !pixmb) {
pixDestroy(&pixmr);
pixDestroy(&pixmg);
pixDestroy(&pixmb);
return (PIX *)ERROR_PTR("not all pixm*", __func__, NULL);
}
pixmri = pixGetInvBackgroundMap(pixmr, bgval, 0, 0);
pixmgi = pixGetInvBackgroundMap(pixmg, bgval, 0, 0);
pixmbi = pixGetInvBackgroundMap(pixmb, bgval, 0, 0);
if (!pixmri || !pixmgi || !pixmbi)
ERROR_PTR("not all pixm*i are made", __func__, NULL);
else
pixd = pixApplyInvBackgroundRGBMap(pixs, pixmri, pixmgi, pixmbi,
reduction, reduction);
pixDestroy(&pixmr);
pixDestroy(&pixmg);
pixDestroy(&pixmb);
pixDestroy(&pixmri);
pixDestroy(&pixmgi);
pixDestroy(&pixmbi);
}
if (!pixd)
ERROR_PTR("pixd not made", __func__, NULL);
pixCopyResolution(pixd, pixs);
return pixd;
}
/*-------------------------------------------------------------------------*
* Arrays of inverted background values for normalization *
*-------------------------------------------------------------------------*
* Notes for these four functions: *
* (1) They are useful if you need to save the actual mapping array. *
* (2) They could be used in the top-level functions but are *
* not because their use makes those functions less clear. *
* (3) Each component in the input pixs generates a 16 bpp pix array. *
*-------------------------------------------------------------------------*/
/*!
* \brief pixBackgroundNormGrayArray()
*
* \param[in] pixs 8 bpp grayscale
* \param[in] pixim [optional] 1 bpp 'image' mask; can be null
* \param[in] sx, sy tile size in pixels
* \param[in] thresh threshold for determining foreground
* \param[in] mincount min threshold on counts in a tile
* \param[in] bgval target bg val; typ. > 128
* \param[in] smoothx half-width of block convolution kernel width
* \param[in] smoothy half-width of block convolution kernel height
* \param[out] ppixd 16 bpp array of inverted background value
* \return 0 if OK, 1 on error
*
* <pre>
* Notes:
* (1) See notes in pixBackgroundNorm().
* (2) This returns a 16 bpp pix that can be used by
* pixApplyInvBackgroundGrayMap() to generate a normalized version
* of the input pixs.
* </pre>
*/
l_ok
pixBackgroundNormGrayArray(PIX *pixs,
PIX *pixim,
l_int32 sx,
l_int32 sy,
l_int32 thresh,
l_int32 mincount,
l_int32 bgval,
l_int32 smoothx,
l_int32 smoothy,
PIX **ppixd)
{
l_int32 allfg;
PIX *pixm;
if (!ppixd)
return ERROR_INT("&pixd not defined", __func__, 1);
*ppixd = NULL;
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not defined or not 8 bpp", __func__, 1);
if (pixGetColormap(pixs))
return ERROR_INT("pixs is colormapped", __func__, 1);
if (pixim && pixGetDepth(pixim) != 1)
return ERROR_INT("pixim not 1 bpp", __func__, 1);
if (sx < 4 || sy < 4)
return ERROR_INT("sx and sy must be >= 4", __func__, 1);
if (mincount > sx * sy) {
L_WARNING("mincount too large for tile size\n", __func__);
mincount = (sx * sy) / 3;
}
/* If pixim exists, verify that it is not all foreground. */
if (pixim) {
pixInvert(pixim, pixim);
pixZero(pixim, &allfg);
pixInvert(pixim, pixim);
if (allfg)
return ERROR_INT("pixim all foreground", __func__, 1);
}
pixGetBackgroundGrayMap(pixs, pixim, sx, sy, thresh, mincount, &pixm);
if (!pixm)
return ERROR_INT("pixm not made", __func__, 1);
*ppixd = pixGetInvBackgroundMap(pixm, bgval, smoothx, smoothy);
pixCopyResolution(*ppixd, pixs);
pixDestroy(&pixm);
return 0;
}
/*!
* \brief pixBackgroundNormRGBArrays()
*
* \param[in] pixs 32 bpp rgb
* \param[in] pixim [optional] 1 bpp 'image' mask; can be null
* \param[in] pixg [optional] 8 bpp grayscale version; can be null
* \param[in] sx, sy tile size in pixels
* \param[in] thresh threshold for determining foreground
* \param[in] mincount min threshold on counts in a tile
* \param[in] bgval target bg val; typ. > 128
* \param[in] smoothx half-width of block convolution kernel width
* \param[in] smoothy half-width of block convolution kernel height
* \param[out] ppixr 16 bpp array of inverted R background value
* \param[out] ppixg 16 bpp array of inverted G background value
* \param[out] ppixb 16 bpp array of inverted B background value
* \return 0 if OK, 1 on error
*
* <pre>
* Notes:
* (1) See notes in pixBackgroundNorm().
* (2) This returns a set of three 16 bpp pix that can be used by
* pixApplyInvBackgroundGrayMap() to generate a normalized version
* of each component of the input pixs.
* </pre>
*/
l_ok
pixBackgroundNormRGBArrays(PIX *pixs,
PIX *pixim,
PIX *pixg,
l_int32 sx,
l_int32 sy,
l_int32 thresh,
l_int32 mincount,
l_int32 bgval,
l_int32 smoothx,
l_int32 smoothy,
PIX **ppixr,
PIX **ppixg,
PIX **ppixb)
{
l_int32 allfg;
PIX *pixmr, *pixmg, *pixmb;
if (!ppixr || !ppixg || !ppixb)
return ERROR_INT("&pixr, &pixg, &pixb not all defined", __func__, 1);
*ppixr = *ppixg = *ppixb = NULL;
if (!pixs)
return ERROR_INT("pixs not defined", __func__, 1);
if (pixGetDepth(pixs) != 32)
return ERROR_INT("pixs not 32 bpp", __func__, 1);
if (pixim && pixGetDepth(pixim) != 1)
return ERROR_INT("pixim not 1 bpp", __func__, 1);
if (sx < 4 || sy < 4)
return ERROR_INT("sx and sy must be >= 4", __func__, 1);
if (mincount > sx * sy) {
L_WARNING("mincount too large for tile size\n", __func__);
mincount = (sx * sy) / 3;
}
/* If pixim exists, verify that it is not all foreground. */
if (pixim) {
pixInvert(pixim, pixim);
pixZero(pixim, &allfg);
pixInvert(pixim, pixim);
if (allfg)
return ERROR_INT("pixim all foreground", __func__, 1);
}
pixGetBackgroundRGBMap(pixs, pixim, pixg, sx, sy, thresh, mincount,
&pixmr, &pixmg, &pixmb);
if (!pixmr || !pixmg || !pixmb) {
pixDestroy(&pixmr);
pixDestroy(&pixmg);
pixDestroy(&pixmb);
return ERROR_INT("not all pixm* made", __func__, 1);
}
*ppixr = pixGetInvBackgroundMap(pixmr, bgval, smoothx, smoothy);
*ppixg = pixGetInvBackgroundMap(pixmg, bgval, smoothx, smoothy);
*ppixb = pixGetInvBackgroundMap(pixmb, bgval, smoothx, smoothy);
pixDestroy(&pixmr);
pixDestroy(&pixmg);
pixDestroy(&pixmb);
return 0;
}
/*!
* \brief pixBackgroundNormGrayArrayMorph()
*
* \param[in] pixs 8 bpp grayscale
* \param[in] pixim [optional] 1 bpp 'image' mask; can be null
* \param[in] reduction at which morph closings are done; between 2 and 16
* \param[in] size of square Sel for the closing; use an odd number
* \param[in] bgval target bg val; typ. > 128
* \param[out] ppixd 16 bpp array of inverted background value
* \return 0 if OK, 1 on error
*
* <pre>
* Notes:
* (1) See notes in pixBackgroundNormMorph().
* (2) This returns a 16 bpp pix that can be used by
* pixApplyInvBackgroundGrayMap() to generate a normalized version
* of the input pixs.
* </pre>
*/
l_ok
pixBackgroundNormGrayArrayMorph(PIX *pixs,
PIX *pixim,
l_int32 reduction,
l_int32 size,
l_int32 bgval,
PIX **ppixd)
{
l_int32 allfg;
PIX *pixm;
if (!ppixd)
return ERROR_INT("&pixd not defined", __func__, 1);
*ppixd = NULL;
if (!pixs)
return ERROR_INT("pixs not defined", __func__, 1);
if (pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not 8 bpp", __func__, 1);
if (pixim && pixGetDepth(pixim) != 1)
return ERROR_INT("pixim not 1 bpp", __func__, 1);
if (reduction < 2 || reduction > 16)
return ERROR_INT("reduction must be between 2 and 16", __func__, 1);
/* If pixim exists, verify that it is not all foreground. */
if (pixim) {
pixInvert(pixim, pixim);
pixZero(pixim, &allfg);
pixInvert(pixim, pixim);
if (allfg)
return ERROR_INT("pixim all foreground", __func__, 1);
}
pixGetBackgroundGrayMapMorph(pixs, pixim, reduction, size, &pixm);
if (!pixm)
return ERROR_INT("pixm not made", __func__, 1);
*ppixd = pixGetInvBackgroundMap(pixm, bgval, 0, 0);
pixCopyResolution(*ppixd, pixs);
pixDestroy(&pixm);
return 0;
}
/*!
* \brief pixBackgroundNormRGBArraysMorph()
*
* \param[in] pixs 32 bpp rgb
* \param[in] pixim [optional] 1 bpp 'image' mask; can be null
* \param[in] reduction at which morph closings are done; between 2 and 16
* \param[in] size of square Sel for the closing; use an odd number
* \param[in] bgval target bg val; typ. > 128
* \param[out] ppixr 16 bpp array of inverted R background value
* \param[out] ppixg 16 bpp array of inverted G background value
* \param[out] ppixb 16 bpp array of inverted B background value
* \return 0 if OK, 1 on error
*
* <pre>
* Notes:
* (1) See notes in pixBackgroundNormMorph().
* (2) This returns a set of three 16 bpp pix that can be used by
* pixApplyInvBackgroundGrayMap() to generate a normalized version
* of each component of the input pixs.
* </pre>
*/
l_ok
pixBackgroundNormRGBArraysMorph(PIX *pixs,
PIX *pixim,
l_int32 reduction,
l_int32 size,
l_int32 bgval,
PIX **ppixr,
PIX **ppixg,
PIX **ppixb)
{
l_int32 allfg;
PIX *pixmr, *pixmg, *pixmb;
if (!ppixr || !ppixg || !ppixb)
return ERROR_INT("&pixr, &pixg, &pixb not all defined", __func__, 1);
*ppixr = *ppixg = *ppixb = NULL;
if (!pixs)
return ERROR_INT("pixs not defined", __func__, 1);
if (pixGetDepth(pixs) != 32)
return ERROR_INT("pixs not 32 bpp", __func__, 1);
if (pixim && pixGetDepth(pixim) != 1)
return ERROR_INT("pixim not 1 bpp", __func__, 1);
if (reduction < 2 || reduction > 16)
return ERROR_INT("reduction must be between 2 and 16", __func__, 1);
/* If pixim exists, verify that it is not all foreground. */
if (pixim) {
pixInvert(pixim, pixim);
pixZero(pixim, &allfg);
pixInvert(pixim, pixim);
if (allfg)
return ERROR_INT("pixim all foreground", __func__, 1);
}
pixGetBackgroundRGBMapMorph(pixs, pixim, reduction, size,
&pixmr, &pixmg, &pixmb);
if (!pixmr || !pixmg || !pixmb) {
pixDestroy(&pixmr);
pixDestroy(&pixmg);
pixDestroy(&pixmb);
return ERROR_INT("not all pixm* made", __func__, 1);
}
*ppixr = pixGetInvBackgroundMap(pixmr, bgval, 0, 0);
*ppixg = pixGetInvBackgroundMap(pixmg, bgval, 0, 0);
*ppixb = pixGetInvBackgroundMap(pixmb, bgval, 0, 0);
pixDestroy(&pixmr);
pixDestroy(&pixmg);
pixDestroy(&pixmb);
return 0;
}
/*------------------------------------------------------------------*
* Measurement of local background *
*------------------------------------------------------------------*/
/*!
* \brief pixGetBackgroundGrayMap()
*
* \param[in] pixs 8 bpp grayscale; not cmapped
* \param[in] pixim [optional] 1 bpp 'image' mask; can be null;
* it should not have only foreground pixels
* \param[in] sx, sy tile size in pixels
* \param[in] thresh threshold for determining foreground
* \param[in] mincount min threshold on counts in a tile
* \param[out] ppixd 8 bpp grayscale map
* \return 0 if OK, 1 on error
*
* <pre>
* Notes:
* (1) The background is measured in regions that don't have
* images. It is then propagated into the image regions,
* and finally smoothed in each image region.
* </pre>
*/
l_ok
pixGetBackgroundGrayMap(PIX *pixs,
PIX *pixim,
l_int32 sx,
l_int32 sy,
l_int32 thresh,
l_int32 mincount,
PIX **ppixd)
{
l_int32 w, h, wd, hd, wim, him, wpls, wplim, wpld, wplf;
l_int32 xim, yim, delx, nx, ny, i, j, k, m;
l_int32 count, sum, val8;
l_int32 empty, fgpixels;
l_uint32 *datas, *dataim, *datad, *dataf, *lines, *lineim, *lined, *linef;
l_float32 scalex, scaley;
PIX *pixd, *piximi, *pixb, *pixf, *pixims;
if (!ppixd)
return ERROR_INT("&pixd not defined", __func__, 1);
*ppixd = NULL;
if (!pixs || pixGetDepth(pixs) != 8)
return ERROR_INT("pixs not defined or not 8 bpp", __func__, 1);
if (pixGetColormap(pixs))
return ERROR_INT("pixs is colormapped", __func__, 1);
if (pixim && pixGetDepth(pixim) != 1)
return ERROR_INT("pixim not 1 bpp", __func__, 1);
if (sx < 4 || sy < 4)
return ERROR_INT("sx and sy must be >= 4", __func__, 1);
if (mincount > sx * sy) {
L_WARNING("mincount too large for tile size\n", __func__);
mincount = (sx * sy) / 3;
}
/* Evaluate the 'image' mask, pixim, and make sure
* it is not all fg. */
fgpixels = 0; /* boolean for existence of fg pixels in the image mask. */
if (pixim) {
piximi = pixInvert(NULL, pixim); /* set non-'image' pixels to 1 */
pixZero(piximi, &empty);
pixDestroy(&piximi);
if (empty)
return ERROR_INT("pixim all fg; no background", __func__, 1);
pixZero(pixim, &empty);
if (!empty) /* there are fg pixels in pixim */
fgpixels = 1;
}
/* Generate the foreground mask, pixf, which is at
* full resolution. These pixels will be ignored when
* computing the background values. */
pixb = pixThresholdToBinary(pixs, thresh);
pixf = pixMorphSequence(pixb, "d7.1 + d1.7", 0);
pixDestroy(&pixb);
if (!pixf)
return ERROR_INT("pixf not made", __func__, 1);
/* ------------- Set up the output map pixd --------------- */
/* Generate pixd, which is reduced by the factors (sx, sy). */
w = pixGetWidth(pixs);
h = pixGetHeight(pixs);
wd = (w + sx - 1) / sx;
hd = (h + sy - 1) / sy;
pixd = pixCreate(wd, hd, 8);
/* Note: we only compute map values in tiles that are complete.
* In general, tiles at right and bottom edges will not be
* complete, and we must fill them in later. */
nx = w / sx;
ny = h / sy;
wpls = pixGetWpl(pixs);
datas = pixGetData(pixs);
wpld = pixGetWpl(pixd);
datad = pixGetData(pixd);
wplf = pixGetWpl(pixf);
dataf = pixGetData(pixf);
for (i = 0; i < ny; i++) {
lines = datas + sy * i * wpls;
linef = dataf + sy * i * wplf;
lined = datad + i * wpld;
for (j = 0; j < nx; j++) {
delx = j * sx;
sum = 0;
count = 0;
for (k = 0; k < sy; k++) {
for (m = 0; m < sx; m++) {
if (GET_DATA_BIT(linef + k * wplf, delx + m) == 0) {
sum += GET_DATA_BYTE(lines + k * wpls, delx + m);
count++;
}
}
}
if (count >= mincount) {
val8 = sum / count;
SET_DATA_BYTE(lined, j, val8);
}
}
}
pixDestroy(&pixf);
/* If there is an optional mask with fg pixels, erase the previous
* calculation for the corresponding map pixels, setting the
* map values to 0. Then, when all the map holes are filled,
* these erased pixels will be set by the surrounding map values.
*
* The calculation here is relatively efficient: for each pixel
* in pixd (which corresponds to a tile of mask pixels in pixim)
* we look only at the pixel in pixim that is at the center
* of the tile. If the mask pixel is ON, we reset the map
* pixel in pixd to 0, so that it can later be filled in. */
pixims = NULL;
if (pixim && fgpixels) {
wim = pixGetWidth(pixim);
him = pixGetHeight(pixim);
dataim = pixGetData(pixim);
wplim = pixGetWpl(pixim);
for (i = 0; i < ny; i++) {
yim = i * sy + sy / 2;
if (yim >= him)
break;
lineim = dataim + yim * wplim;
for (j = 0; j < nx; j++) {
xim = j * sx + sx / 2;
if (xim >= wim)
break;
if (GET_DATA_BIT(lineim, xim))
pixSetPixel(pixd, j, i, 0);
}
}
}
/* Fill all the holes in the map. */
if (pixFillMapHoles(pixd, nx, ny, L_FILL_BLACK)) {
pixDestroy(&pixd);
L_WARNING("can't make the map\n", __func__);
return 1;
}
/* Finally, for each connected region corresponding to the
* 'image' mask, reset all pixels to their average value.
* Each of these components represents an image (or part of one)
* in the input, and this smooths the background values
* in each of these regions. */
if (pixim && fgpixels) {