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Pull new pixCleanImage() out of cleanTo1bppFilesToPdf()
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* Also, allow for the input to be 1 bpp.
* Test the new function for 1 bpp and grayscale in prog/misctest1
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@DanBloomberg
DanBloomberg committed Aug 31, 2023
1 parent df0fe14 commit 4621261
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Showing 5 changed files with 146 additions and 33 deletions.
1 change: 1 addition & 0 deletions prog/cleanpdf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -263,5 +263,6 @@ SARRAY *sa;
lept_stderr("cleaning ...\n");
cleanTo1bppFilesToPdf(sa, res, contrast, rotation, opensize,
title, fileout);
sarrayDestroy(&sa);
return 0;
}
24 changes: 24 additions & 0 deletions prog/misctest1.c
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@
* * Display differences in images with pixDisplayDiff()
* * Demonstrate read of cmap+alpha png, and I/O of rgba pnm, bmp, webp
* * Demonstrate image cropping function
* * Demonstrate image cleaning function
*/

#ifdef HAVE_CONFIG_H
Expand Down Expand Up @@ -420,5 +421,28 @@ PIXCMAP *cmap, *cmapg;
pixDestroy(&pix1);
pixDestroy(&pix2);

/* Page cleaning */
pixa1 = pixaCreate(3);
pix1 = pixRead("tel_3.tif");
pix2 = pixRotate(pix1, 0.02, L_ROTATE_SAMPLING, L_BRING_IN_WHITE, 0, 0);
pix3 = pixCleanImage(pix2, 1, 0, 1, 0);
pixaAddPix(pixa1, pix3, L_INSERT);
pixDisplay(pix3, 800, 800);
pixDestroy(&pix1);
pixDestroy(&pix2);
pix1 = pixRead("w91frag.jpg");
pixaAddPix(pixa1, pixScale(pix1, 2.5, 2.5), L_INSERT);
pix2 = pixRotate(pix1, 0.02, L_ROTATE_AREA_MAP, L_BRING_IN_WHITE, 0, 0);
pix3 = pixCleanImage(pix2, 1, 0, 1, 0);
pixaAddPix(pixa1, pixScale(pix3, 2.5, 2.5), L_INSERT);
pixDisplay(pix3, 1200, 800);
pixDestroy(&pix1);
pixDestroy(&pix2);
pixDestroy(&pix3);
lept_stderr("Writing /tmp/lept/misc/pageclean.pdf\n");
pixaConvertToPdf(pixa1, 0, 1.0, L_DEFAULT_ENCODE, 50, NULL,
"/tmp/lept/misc/pageclean.pdf");
pixaDestroy(&pixa1);

return 0;
}
1 change: 1 addition & 0 deletions src/allheaders.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1376,6 +1376,7 @@ LEPT_DLL extern PIX * pixGenerateHalftoneMask ( PIX *pixs, PIX **ppixtext, l_int
LEPT_DLL extern PIX * pixGenTextlineMask ( PIX *pixs, PIX **ppixvws, l_int32 *ptlfound, PIXA *pixadb );
LEPT_DLL extern PIX * pixGenTextblockMask ( PIX *pixs, PIX *pixvws, PIXA *pixadb );
LEPT_DLL extern PIX * pixCropImage ( PIX *pixs, l_int32 lr_clear, l_int32 tb_clear, l_int32 edgeclean, l_int32 lr_add, l_int32 tb_add, const char *debugfile, BOX **pcropbox );
LEPT_DLL extern PIX * pixCleanImage ( PIX *pixs, l_int32 contrast, l_int32 rotation, l_int32 scale, l_int32 opensize );
LEPT_DLL extern BOX * pixFindPageForeground ( PIX *pixs, l_int32 threshold, l_int32 mindist, l_int32 erasedist, l_int32 showmorph, PIXAC *pixac );
LEPT_DLL extern l_ok pixSplitIntoCharacters ( PIX *pixs, l_int32 minw, l_int32 minh, BOXA **pboxa, PIXA **ppixa, PIX **ppixdebug );
LEPT_DLL extern BOXA * pixSplitComponentWithProfile ( PIX *pixs, l_int32 delta, l_int32 mindel, PIX **ppixdebug );
Expand Down
106 changes: 104 additions & 2 deletions src/pageseg.c
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Original file line number Diff line number Diff line change
Expand Up @@ -42,8 +42,9 @@
* Textblock extraction
* PIX *pixGenTextblockMask()
*
* Location and extraction of page foreground
* Location and extraction of page foreground; cleaning pages
* PIX *pixCropImage()
* PIX *pixCleanImage()
* BOX *pixFindPageForeground()
*
* Extraction of characters from image with only text
Expand Down Expand Up @@ -524,7 +525,7 @@ PIX *pix1, *pix2, *pix3, *pixd;


/*------------------------------------------------------------------*
* Location of page foreground *
* Location and extraction of page foreground; cleaning pages *
*------------------------------------------------------------------*/
/*!
* \brief pixCropImage()
Expand Down Expand Up @@ -689,6 +690,107 @@ BOX *box1, *box2;
}


/*!
* \brief pixCleanImage()
*
* \param[in] pixs full resolution (any type or depth)
* \param[in] contrast vary contrast: 1 = lightest; 10 = darkest;
* suggest 1 unless light features are being lost
* \param[in] rotation cw by 90 degrees: {0,1,2,3} represent
* 0, 90, 180 and 270 degree cw rotations
* \param[in] scale 1 (no scaling) or 2 (2x upscaling)
* \param[in] opensize opening size of structuring element for noise
* removal: {0 or 1 to skip; 2, 3 for opening}
* \return cleaned pix, or NULL on error
*
* <pre>
* Notes:
* (1) This deskews, optionally rotates and darkens, cleans background
* to white, binarizes and optionally removes small noise.
* (2) For color and grayscale input, local background normalization is
* done to 200, and a threshold of 180 sets the maximum foreground
* value in the normalized image.
* (3) The %contrast parameter adjusts the binarization to avoid losing
* lighter input pixels. Contrast is increased as %contrast increases
* from 1 to 10.
* (4) The %scale parameter controls the thresholding to 1 bpp. Two values:
* 1 = threshold
* 2 = linear interpolated 2x upscaling before threshold.
* (5) The #opensize parameter is the size of a square SEL used with
* opening to remove small speckle noise. Allowed open sizes are 2,3.
* If this is to be used, try 2 before 3.
* (6) This does the image processing for cleanTo1bppFilesToPdf() and
* prog/cleanpdf.c.
* </pre>
*/
PIX *
pixCleanImage(PIX *pixs,
l_int32 contrast,
l_int32 rotation,
l_int32 scale,
l_int32 opensize)
{
char sequence[32];
PIX *pix1, *pix2, *pix3, *pix4, *pix5;

if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
if (rotation < 0 || rotation > 3) {
L_ERROR("invalid rotation = %d; rotation must be in {0,1,2,3}\n",
__func__, rotation);
return NULL;
}
if (contrast < 1 || contrast > 10) {
L_ERROR("invalid contrast = %d; contrast must be in [1...10]\n",
__func__, contrast);
return NULL;
}
if (scale != 1 && scale != 2) {
L_ERROR("invalid scale = %d; scale must be 1 or 2\n",
__func__, opensize);
return NULL;
}
if (opensize > 3) {
L_ERROR("invalid opensize = %d; opensize must be <= 3\n",
__func__, opensize);
return NULL;
}

if (pixGetDepth(pixs) == 1) {
if (rotation > 0)
pix1 = pixRotateOrth(pixs, rotation);
else
pix1 = pixClone(pixs);
pix2 = pixFindSkewAndDeskew(pix1, 2, NULL, NULL);
if (scale == 2)
pix4 = pixExpandBinaryReplicate(pix2, 2, 2);
else /* scale == 1 */
pix4 = pixClone(pix2);
} else {
pix1 = pixConvertTo8MinMax(pixs);
if (rotation > 0)
pix2 = pixRotateOrth(pix1, rotation);
else
pix2 = pixClone(pix1);
pix3 = pixFindSkewAndDeskew(pix2, 2, NULL, NULL);
pix4 = pixBackgroundNormTo1MinMax(pix3, contrast, scale);
pixDestroy(&pix3);
}

if (opensize == 2 || opensize == 3) {
snprintf(sequence, sizeof(sequence), "o%d.%d", opensize, opensize);
pix5 = pixMorphSequence(pix4, sequence, 0);
} else {
pix5 = pixClone(pix4);
}

pixDestroy(&pix1);
pixDestroy(&pix2);
pixDestroy(&pix4);
return pix5;
}


/*!
* \brief pixFindPageForeground()
*
Expand Down
47 changes: 16 additions & 31 deletions src/pdfapp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -324,7 +324,7 @@ PIXAC *pixac1 = NULL;
* \param[in] rotation cw by 90 degrees: {0,1,2,3} represent
* 0, 90, 180 and 270 degree cw rotations
* \param[in] opensize opening size of structuring element for noise
* removal: {0 to skip; 2, 3}
* removal: {0 or 1to skip; 2, 3 for opening}
* \param[in] title [optional] pdf title; can be null
* \param[in] fileout pdf file of all images
* \return 0 if OK, 1 on error
Expand All @@ -334,21 +334,20 @@ PIXAC *pixac1 = NULL;
* (1) This deskews, optionally rotates and darkens, cleans background
* to white, binarizes and optionally removes small noise, and
* put the images into the pdf in the order given in %sa.
* (2) It does the image processing for prog/cleanpdf.c.
* (3) All images in the pdf are tiffg4 encoded.
* (4) For color and grayscale input, local background normalization is
* (2) All images in the pdf are tiffg4 encoded.
* (3) For color and grayscale input, local background normalization is
* done to 200, and a threshold of 180 sets the maximum foreground
* value in the normalized image.
* (5) The %res parameter can be either 300 or 600 ppi. If the input
* (4) The %res parameter can be either 300 or 600 ppi. If the input
* is gray or color and %res = 600, this does an interpolated 2x
* expansion before binarizing.
* (6) The %contrast parameter adjusts the binarization to avoid losing
* (5) The %contrast parameter adjusts the binarization to avoid losing
* lighter input pixels. Contrast is increased as %contrast increases
* from 1 to 10.
* (7) The #opensize parameter is the size of a square SEL used with
* (6) The #opensize parameter is the size of a square SEL used with
* opening to remove small speckle noise. Allowed open sizes are 2,3.
* If this is to be used, try 2 before 3.
* (8) If there are more than 200 images, store the images after processing
* (7) If there are more than 200 images, store the images after processing
* as an array of compressed images (a Pixac); otherwise, use a Pixa.
* </pre>
*/
Expand All @@ -361,11 +360,10 @@ cleanTo1bppFilesToPdf(SARRAY *sa,
const char *title,
const char *fileout)
{
char sequence[32];
char *fname;
l_int32 n, i, scale;
l_int32 maxsmallset = 200; /* max num images kept uncompressed in array */
PIX *pixs, *pix1, *pix2, *pix3, *pix4, *pix5;
PIX *pixs, *pix1;
PIXA *pixa1 = NULL;
PIXAC *pixac1 = NULL;

Expand Down Expand Up @@ -408,31 +406,19 @@ PIXAC *pixac1 = NULL;
else if (i % 10 == 0)
lept_stderr("%d . ", i);
fname = sarrayGetString(sa, i, L_NOCOPY);
pixs = pixRead(fname);
pix1 = pixConvertTo8MinMax(pixs);
if (rotation > 0)
pix2 = pixRotateOrth(pix1, rotation);
else
pix2 = pixClone(pix1);
pix3 = pixFindSkewAndDeskew(pix2, 2, NULL, NULL);
pix4 = pixBackgroundNormTo1MinMax(pix3, contrast, scale);
if (opensize == 2 || opensize == 3) {
snprintf(sequence, sizeof(sequence), "o%d.%d", opensize, opensize);
pix5 = pixMorphSequence(pix4, sequence, 0);
} else {
pix5 = pixClone(pix4);
if ((pixs = pixRead(fname)) == NULL) {
L_ERROR("pixs not read from %s\n", __func__, fname);
continue;
}

pix1 = pixCleanImage(pixs, contrast, rotation, scale, opensize);
if (n <= maxsmallset) {
pixaAddPix(pixa1, pix5, L_INSERT);
pixaAddPix(pixa1, pix1, L_INSERT);
} else {
pixacompAddPix(pixac1, pix5, IFF_TIFF_G4);
pixDestroy(&pix5);
pixacompAddPix(pixac1, pix1, IFF_TIFF_G4);
pixDestroy(&pix1);
}
pixDestroy(&pixs);
pixDestroy(&pix1);
pixDestroy(&pix2);
pixDestroy(&pix3);
pixDestroy(&pix4);
}

/* Generate the pdf. Compute the actual input resolution from
Expand All @@ -455,7 +441,6 @@ PIXAC *pixac1 = NULL;
pixacompConvertToPdf(pixac1, res, 1.0, L_G4_ENCODE, 0, title, fileout);
pixacompDestroy(&pixac1);
}

return 0;
}

Expand Down

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