Image::Leptonica::Func::pix3
version 0.04
pix3.c
pix3.c This file has these operations: (1) Mask-directed operations (2) Full-image bit-logical operations (3) Foreground pixel counting operations on 1 bpp images (4) Average and variance of pixel values (5) Mirrored tiling of a smaller image Masked operations l_int32 pixSetMasked() l_int32 pixSetMaskedGeneral() l_int32 pixCombineMasked() l_int32 pixCombineMaskedGeneral() l_int32 pixPaintThroughMask() PIX *pixPaintSelfThroughMask() PIX *pixMakeMaskFromLUT() PIX *pixSetUnderTransparency() One and two-image boolean operations on arbitrary depth images PIX *pixInvert() PIX *pixOr() PIX *pixAnd() PIX *pixXor() PIX *pixSubtract() Foreground pixel counting in 1 bpp images l_int32 pixZero() l_int32 pixForegroundFraction() NUMA *pixaCountPixels() l_int32 pixCountPixels() NUMA *pixCountByRow() NUMA *pixCountByColumn() NUMA *pixCountPixelsByRow() NUMA *pixCountPixelsByColumn() l_int32 pixCountPixelsInRow() NUMA *pixGetMomentByColumn() l_int32 pixThresholdPixelSum() l_int32 *makePixelSumTab8() l_int32 *makePixelCentroidTab8() Average of pixel values in gray images NUMA *pixAverageByRow() NUMA *pixAverageByColumn() l_int32 pixAverageInRect() Variance of pixel values in gray images NUMA *pixVarianceByRow() NUMA *pixVarianceByColumn() l_int32 pixVarianceInRect() Average of absolute value of pixel differences in gray images NUMA *pixAbsDiffByRow() NUMA *pixAbsDiffByColumn() l_int32 pixAbsDiffInRect() l_int32 pixAbsDiffOnLine() Count of pixels with specific value * l_int32 pixCountArbInRect() Mirrored tiling PIX *pixMirroredTiling() Static helper function static l_int32 findTilePatchCenter()
l_int32 * makePixelCentroidTab8 ( void )
makePixelCentroidTab8() Input: void Return: table of 256 l_int32, or null on error Notes: (1) This table of integers gives the centroid weight of the 1 bits in the 8 bit index. In other words, if sumtab is obtained by makePixelSumTab8, and centroidtab is obtained by makePixelCentroidTab8, then, for 1 <= i <= 255, centroidtab[i] / (float)sumtab[i] is the centroid of the 1 bits in the 8-bit index i, where the MSB is considered to have position 0 and the LSB is considered to have position 7.
l_int32 * makePixelSumTab8 ( void )
makePixelSumTab8() Input: void Return: table of 256 l_int32, or null on error Notes: (1) This table of integers gives the number of 1 bits in the 8 bit index.
NUMA * pixAbsDiffByColumn ( PIX *pix, BOX *box )
pixAbsDiffByColumn() Input: pix (8 bpp; no colormap) box (<optional> clipping box for region; can be null) Return: na of abs val pixel difference averages by column, or null on error Notes: (1) This is an average over differences of adjacent pixels along each column. (2) To resample for a bin size different from 1, use numaUniformSampling() on the result of this function.
NUMA * pixAbsDiffByRow ( PIX *pix, BOX *box )
pixAbsDiffByRow() Input: pix (8 bpp; no colormap) box (<optional> clipping box for region; can be null) Return: na of abs val pixel difference averages by row, or null on error Notes: (1) This is an average over differences of adjacent pixels along each row. (2) To resample for a bin size different from 1, use numaUniformSampling() on the result of this function.
l_int32 pixAbsDiffInRect ( PIX *pix, BOX *box, l_int32 dir, l_float32 *pabsdiff )
pixAbsDiffInRect() Input: pix (8 bpp; not cmapped) box (<optional> if null, use entire image) dir (differences along L_HORIZONTAL_LINE or L_VERTICAL_LINE) &absdiff (<return> average of abs diff pixel values in region) Return: 0 if OK; 1 on error Notes: (1) This gives the average over the abs val of differences of adjacent pixels values, along either each row: dir == L_HORIZONTAL_LINE column: dir == L_VERTICAL_LINE
l_int32 pixAbsDiffOnLine ( PIX *pix, l_int32 x1, l_int32 y1, l_int32 x2, l_int32 y2, l_float32 *pabsdiff )
pixAbsDiffOnLine() Input: pix (8 bpp; not cmapped) x1, y1 (first point; x1 <= x2, y1 <= y2) x2, y2 (first point) &absdiff (<return> average of abs diff pixel values on line) Return: 0 if OK; 1 on error Notes: (1) This gives the average over the abs val of differences of adjacent pixels values, along a line that is either horizontal or vertical. (2) If horizontal, require x1 < x2; if vertical, require y1 < y2.
PIX * pixAnd ( PIX *pixd, PIX *pixs1, PIX *pixs2 )
pixAnd() Input: pixd (<optional>; this can be null, equal to pixs1, different from pixs1) pixs1 (can be == pixd) pixs2 (must be != pixd) Return: pixd always Notes: (1) This gives the intersection of two images with equal depth, aligning them to the the UL corner. pixs1 and pixs2 need not have the same width and height. (2) There are 3 cases: (a) pixd == null, (src1 & src2) --> new pixd (b) pixd == pixs1, (src1 & src2) --> src1 (in-place) (c) pixd != pixs1, (src1 & src2) --> input pixd (3) For clarity, if the case is known, use these patterns: (a) pixd = pixAnd(NULL, pixs1, pixs2); (b) pixAnd(pixs1, pixs1, pixs2); (c) pixAnd(pixd, pixs1, pixs2); (4) The size of the result is determined by pixs1. (5) The depths of pixs1 and pixs2 must be equal. (6) Note carefully that the order of pixs1 and pixs2 only matters for the in-place case. For in-place, you must have pixd == pixs1. Setting pixd == pixs2 gives an incorrect result: the copy puts pixs1 image data in pixs2, and the rasterop is then between pixs2 and pixs2 (a no-op).
NUMA * pixAverageByColumn ( PIX *pix, BOX *box, l_int32 type )
pixAverageByColumn() Input: pix (8 or 16 bpp; no colormap) box (<optional> clipping box for sum; can be null) type (L_WHITE_IS_MAX, L_BLACK_IS_MAX) Return: na of pixel averages by column, or null on error Notes: (1) To resample for a bin size different from 1, use numaUniformSampling() on the result of this function. (2) If type == L_BLACK_IS_MAX, black pixels get the maximum value (0xff for 8 bpp, 0xffff for 16 bpp) and white get 0.
NUMA * pixAverageByRow ( PIX *pix, BOX *box, l_int32 type )
pixAverageByRow() Input: pix (8 or 16 bpp; no colormap) box (<optional> clipping box for sum; can be null) type (L_WHITE_IS_MAX, L_BLACK_IS_MAX) Return: na of pixel averages by row, or null on error Notes: (1) To resample for a bin size different from 1, use numaUniformSampling() on the result of this function. (2) If type == L_BLACK_IS_MAX, black pixels get the maximum value (0xff for 8 bpp, 0xffff for 16 bpp) and white get 0.
l_int32 pixAverageInRect ( PIX *pix, BOX *box, l_float32 *pave )
pixAverageInRect() Input: pix (1, 2, 4, 8 bpp; not cmapped) box (<optional> if null, use entire image) &ave (<return> average of pixel values in region) Return: 0 if OK; 1 on error
l_int32 pixCombineMasked ( PIX *pixd, PIX *pixs, PIX *pixm )
pixCombineMasked() Input: pixd (1 bpp, 8 bpp gray or 32 bpp rgb; no cmap) pixs (1 bpp, 8 bpp gray or 32 bpp rgb; no cmap) pixm (<optional> 1 bpp mask; no operation if NULL) Return: 0 if OK; 1 on error Notes: (1) In-place operation; pixd is changed. (2) This sets each pixel in pixd that co-locates with an ON pixel in pixm to the corresponding value of pixs. (3) pixs and pixd must be the same depth and not colormapped. (4) All three input pix are aligned at the UL corner, and the operation is clipped to the intersection of all three images. (5) If pixm == NULL, it's a no-op. (6) Implementation: see notes in pixCombineMaskedGeneral(). For 8 bpp selective masking, you might guess that it would be faster to generate an 8 bpp version of pixm, using pixConvert1To8(pixm, 0, 255), and then use a general combine operation d = (d & ~m) | (s & m) on a word-by-word basis. Not always. The word-by-word combine takes a time that is independent of the mask data. If the mask is relatively sparse, the byte-check method is actually faster!
l_int32 pixCombineMaskedGeneral ( PIX *pixd, PIX *pixs, PIX *pixm, l_int32 x, l_int32 y )
pixCombineMaskedGeneral() Input: pixd (1 bpp, 8 bpp gray or 32 bpp rgb) pixs (1 bpp, 8 bpp gray or 32 bpp rgb) pixm (<optional> 1 bpp mask) x, y (origin of pixs and pixm relative to pixd; can be negative) Return: 0 if OK; 1 on error Notes: (1) In-place operation; pixd is changed. (2) This is a generalized version of pixCombinedMasked(), where the source and mask can be placed at the same (arbitrary) location relative to pixd. (3) pixs and pixd must be the same depth and not colormapped. (4) The UL corners of both pixs and pixm are aligned with the point (x, y) of pixd, and the operation is clipped to the intersection of all three images. (5) If pixm == NULL, it's a no-op. (6) Implementation. There are two ways to do these. In the first, we use rasterop, ORing the part of pixs under the mask with pixd (which has been appropriately cleared there first). In the second, the mask is used one pixel at a time to selectively replace pixels of pixd with those of pixs. Here, we use rasterop for 1 bpp and pixel-wise replacement for 8 and 32 bpp. To use rasterop for 8 bpp, for example, we must first generate an 8 bpp version of the mask. The code is simple: Pix *pixm8 = pixConvert1To8(NULL, pixm, 0, 255); Pix *pixt = pixAnd(NULL, pixs, pixm8); pixRasterop(pixd, x, y, wmin, hmin, PIX_DST & PIX_NOT(PIX_SRC), pixm8, 0, 0); pixRasterop(pixd, x, y, wmin, hmin, PIX_SRC | PIX_DST, pixt, 0, 0); pixDestroy(&pixt); pixDestroy(&pixm8);
l_int32 pixCountArbInRect ( PIX *pixs, BOX *box, l_int32 val, l_int32 factor, l_int32 *pcount )
pixCountArbInRect() Input: pixs (8 bpp, or colormapped) box (<optional>) over which count is made; use entire image null) val (pixel value to count) factor (subsampling factor; integer >= 1) &count (<return> count; estimate it if factor > 1) Return: na (histogram), or null on error Notes: (1) If pixs is cmapped, @val is compared to the colormap index; otherwise, @val is compared to the grayscale value. (2) Set the subsampling @factor > 1 to reduce the amount of computation. If @factor > 1, multiply the count by @factor * @factor.
NUMA * pixCountByColumn ( PIX *pix, BOX *box )
pixCountByColumn() Input: pix (1 bpp) box (<optional> clipping box for count; can be null) Return: na of number of ON pixels by column, or null on error Notes: (1) To resample for a bin size different from 1, use numaUniformSampling() on the result of this function.
NUMA * pixCountByRow ( PIX *pix, BOX *box )
pixCountByRow() Input: pix (1 bpp) box (<optional> clipping box for count; can be null) Return: na of number of ON pixels by row, or null on error Notes: (1) To resample for a bin size different from 1, use numaUniformSampling() on the result of this function.
l_int32 pixCountPixels ( PIX *pix, l_int32 *pcount, l_int32 *tab8 )
pixCountPixels() Input: pix (1 bpp) &count (<return> count of ON pixels) tab8 (<optional> 8-bit pixel lookup table) Return: 0 if OK; 1 on error
NUMA * pixCountPixelsByColumn ( PIX *pix )
pixCountPixelsByColumn() Input: pix (1 bpp) Return: na of counts in each column, or null on error
NUMA * pixCountPixelsByRow ( PIX *pix, l_int32 *tab8 )
pixCountPixelsByRow() Input: pix (1 bpp) tab8 (<optional> 8-bit pixel lookup table) Return: na of counts, or null on error
l_int32 pixCountPixelsInRow ( PIX *pix, l_int32 row, l_int32 *pcount, l_int32 *tab8 )
pixCountPixelsInRow() Input: pix (1 bpp) row number &count (<return> sum of ON pixels in raster line) tab8 (<optional> 8-bit pixel lookup table) Return: 0 if OK; 1 on error
l_int32 pixForegroundFraction ( PIX *pix, l_float32 *pfract )
pixForegroundFraction() Input: pix (1 bpp) &fract (<return> fraction of ON pixels) Return: 0 if OK; 1 on error
NUMA * pixGetMomentByColumn ( PIX *pix, l_int32 order )
pixGetMomentByColumn() Input: pix (1 bpp) order (of moment, either 1 or 2) Return: na of first moment of fg pixels, by column, or null on error
PIX * pixInvert ( PIX *pixd, PIX *pixs )
pixInvert() Input: pixd (<optional>; this can be null, equal to pixs, or different from pixs) pixs Return: pixd, or null on error Notes: (1) This inverts pixs, for all pixel depths. (2) There are 3 cases: (a) pixd == null, ~src --> new pixd (b) pixd == pixs, ~src --> src (in-place) (c) pixd != pixs, ~src --> input pixd (3) For clarity, if the case is known, use these patterns: (a) pixd = pixInvert(NULL, pixs); (b) pixInvert(pixs, pixs); (c) pixInvert(pixd, pixs);
PIX * pixMakeMaskFromLUT ( PIX *pixs, l_int32 *tab )
pixMakeMaskFromLUT() Input: pixs (2, 4 or 8 bpp; can be colormapped) tab (256-entry LUT; 1 means to write to mask) Return: pixd (1 bpp mask), or null on error Notes: (1) This generates a 1 bpp mask image, where a 1 is written in the mask for each pixel in pixs that has a value corresponding to a 1 in the LUT. (2) The LUT should be of size 256.
PIX * pixMirroredTiling ( PIX *pixs, l_int32 w, l_int32 h )
pixMirroredTiling() Input: pixs (8 or 32 bpp, small tile; to be replicated) w, h (dimensions of output pix) Return: pixd (usually larger pix, mirror-tiled with pixs), or null on error Notes: (1) This uses mirrored tiling, where each row alternates with LR flips and every column alternates with TB flips, such that the result is a tiling with identical 2 x 2 tiles, each of which is composed of these transforms: ----------------- | 1 | LR | ----------------- | TB | LR/TB | -----------------
PIX * pixOr ( PIX *pixd, PIX *pixs1, PIX *pixs2 )
pixOr() Input: pixd (<optional>; this can be null, equal to pixs1, different from pixs1) pixs1 (can be == pixd) pixs2 (must be != pixd) Return: pixd always Notes: (1) This gives the union of two images with equal depth, aligning them to the the UL corner. pixs1 and pixs2 need not have the same width and height. (2) There are 3 cases: (a) pixd == null, (src1 | src2) --> new pixd (b) pixd == pixs1, (src1 | src2) --> src1 (in-place) (c) pixd != pixs1, (src1 | src2) --> input pixd (3) For clarity, if the case is known, use these patterns: (a) pixd = pixOr(NULL, pixs1, pixs2); (b) pixOr(pixs1, pixs1, pixs2); (c) pixOr(pixd, pixs1, pixs2); (4) The size of the result is determined by pixs1. (5) The depths of pixs1 and pixs2 must be equal. (6) Note carefully that the order of pixs1 and pixs2 only matters for the in-place case. For in-place, you must have pixd == pixs1. Setting pixd == pixs2 gives an incorrect result: the copy puts pixs1 image data in pixs2, and the rasterop is then between pixs2 and pixs2 (a no-op).
l_int32 pixPaintSelfThroughMask ( PIX *pixd, PIX *pixm, l_int32 x, l_int32 y, l_int32 tilesize, l_int32 searchdir )
pixPaintSelfThroughMask() Input: pixd (8 bpp gray or 32 bpp rgb; not colormapped) pixm (1 bpp mask) x, y (origin of pixm relative to pixd; must not be negative) tilesize (requested size for tiling) searchdir (L_HORIZ, L_VERT) Return: 0 if OK; 1 on error Notes: (1) In-place operation; pixd is changed. (2) If pixm == NULL, it's a no-op. (3) The mask origin is placed at (x,y) on pixd, and the operation is clipped to the intersection of pixd and the fg of the mask. (4) The tilesize is the the requested size for tiling. The actual size for each c.c. will be bounded by the minimum dimension of the c.c. and the distance at which the tile center is located. (5) searchdir is the direction with respect to the b.b. of each mask component, from which the square patch is chosen and tiled onto the image, clipped by the mask component. (6) Specifically, a mirrored tiling, generated from pixd, is used to construct the pixels that are painted onto pixd through pixm.
l_int32 pixPaintThroughMask ( PIX *pixd, PIX *pixm, l_int32 x, l_int32 y, l_uint32 val )
pixPaintThroughMask() Input: pixd (1, 2, 4, 8, 16 or 32 bpp; or colormapped) pixm (<optional> 1 bpp mask) x, y (origin of pixm relative to pixd; can be negative) val (pixel value to set at each masked pixel) Return: 0 if OK; 1 on error Notes: (1) In-place operation. Calls pixSetMaskedCmap() for colormapped images. (2) For 1, 2, 4, 8 and 16 bpp gray, we take the appropriate number of least significant bits of val. (3) If pixm == NULL, it's a no-op. (4) The mask origin is placed at (x,y) on pixd, and the operation is clipped to the intersection of rectangles. (5) For rgb, the components in val are in the canonical locations, with red in location COLOR_RED, etc. (6) Implementation detail 1: For painting with val == 0 or val == maxval, you can use rasterop. If val == 0, invert the mask so that it's 0 over the region into which you want to write, and use PIX_SRC & PIX_DST to clear those pixels. To write with val = maxval (all 1's), use PIX_SRC | PIX_DST to set all bits under the mask. (7) Implementation detail 2: The rasterop trick can be used for depth > 1 as well. For val == 0, generate the mask for depth d from the binary mask using pixmd = pixUnpackBinary(pixm, d, 1); and use pixRasterop() with PIX_MASK. For val == maxval, pixmd = pixUnpackBinary(pixm, d, 0); and use pixRasterop() with PIX_PAINT. But note that if d == 32 bpp, it is about 3x faster to use the general implementation (not pixRasterop()). (8) Implementation detail 3: It might be expected that the switch in the inner loop will cause large branching delays and should be avoided. This is not the case, because the entrance is always the same and the compiler can correctly predict the jump.
l_int32 pixSetMasked ( PIX *pixd, PIX *pixm, l_uint32 val )
pixSetMasked() Input: pixd (1, 2, 4, 8, 16 or 32 bpp; or colormapped) pixm (<optional> 1 bpp mask; no operation if NULL) val (value to set at each masked pixel) Return: 0 if OK; 1 on error Notes: (1) In-place operation. (2) NOTE: For cmapped images, this calls pixSetMaskedCmap(). @val must be the 32-bit color representation of the RGB pixel. It is not the index into the colormap! (2) If pixm == NULL, a warning is given. (3) This is an implicitly aligned operation, where the UL corners of pixd and pixm coincide. A warning is issued if the two image sizes differ significantly, but the operation proceeds. (4) Each pixel in pixd that co-locates with an ON pixel in pixm is set to the specified input value. Other pixels in pixd are not changed. (5) You can visualize this as painting the color through the mask, as a stencil. (6) If you do not want to have the UL corners aligned, use the function pixSetMaskedGeneral(), which requires you to input the UL corner of pixm relative to pixd. (7) Implementation details: see comments in pixPaintThroughMask() for when we use rasterop to do the painting.
l_int32 pixSetMaskedGeneral ( PIX *pixd, PIX *pixm, l_uint32 val, l_int32 x, l_int32 y )
pixSetMaskedGeneral() Input: pixd (8, 16 or 32 bpp) pixm (<optional> 1 bpp mask; no operation if null) val (value to set at each masked pixel) x, y (location of UL corner of pixm relative to pixd; can be negative) Return: 0 if OK; 1 on error Notes: (1) This is an in-place operation. (2) Alignment is explicit. If you want the UL corners of the two images to be aligned, use pixSetMasked(). (3) A typical use would be painting through the foreground of a small binary mask pixm, located somewhere on a larger pixd. Other pixels in pixd are not changed. (4) You can visualize this as painting the color through the mask, as a stencil. (5) This uses rasterop to handle clipping and different depths of pixd. (6) If pixd has a colormap, you should call pixPaintThroughMask(). (7) Why is this function here, if pixPaintThroughMask() does the same thing, and does it more generally? I've retained it here to show how one can paint through a mask using only full image rasterops, rather than pixel peeking in pixm and poking in pixd. It's somewhat baroque, but I found it amusing.
PIX * pixSetUnderTransparency ( PIX *pixs, l_uint32 val, l_int32 debug )
pixSetUnderTransparency() Input: pixs (32 bpp rgba) val (32 bit unsigned color to use where alpha == 0) debug (displays layers of pixs) Return: pixd (32 bpp rgba), or null on error Notes: (1) This sets the r, g and b components under every fully transparent alpha component to @val. The alpha components are unchanged. (2) Full transparency is denoted by alpha == 0. Setting all pixels to a constant @val where alpha is transparent can improve compressibility by reducing the entropy. (3) The visual result depends on how the image is displayed. (a) For display devices that respect the use of the alpha layer, this will not affect the appearance. (b) For typical leptonica operations, alpha is ignored, so there will be a change in appearance because this resets the rgb values in the fully transparent region. (4) pixRead() and pixWrite() will, by default, read and write 4-component (rgba) pix in png format. To ignore the alpha component after reading, or omit it on writing, pixSetSpp(..., 3). (5) Here are some examples: * To convert all fully transparent pixels in a 4 component (rgba) png file to white: pixs = pixRead(<infile>); pixd = pixSetUnderTransparency(pixs, 0xffffff00, 0); * To write pixd with the alpha component: pixWrite(<outfile>, pixd, IFF_PNG); * To write and rgba image without the alpha component, first do: pixSetSpp(pixd, 3); If you later want to use the alpha, spp must be reset to 4. * (fancier) To remove the alpha by blending the image over a white background: pixRemoveAlpha() This changes all pixel values where the alpha component is not opaque (255). (6) Caution. rgb images in leptonica typically have value 0 in the alpha channel, which is fully transparent. If spp for such an image were changed from 3 to 4, the image becomes fully transparent, and this function will set each pixel to @val. If you really want to set every pixel to the same value, use pixSetAllArbitrary(). (7) This is useful for compressing an RGBA image where the part of the image that is fully transparent is random junk; compression is typically improved by setting that region to a constant. For rendering as a 3 component RGB image over a uniform background of arbitrary color, use pixAlphaBlendUniform().
PIX * pixSubtract ( PIX *pixd, PIX *pixs1, PIX *pixs2 )
pixSubtract() Input: pixd (<optional>; this can be null, equal to pixs1, equal to pixs2, or different from both pixs1 and pixs2) pixs1 (can be == pixd) pixs2 (can be == pixd) Return: pixd always Notes: (1) This gives the set subtraction of two images with equal depth, aligning them to the the UL corner. pixs1 and pixs2 need not have the same width and height. (2) Source pixs2 is always subtracted from source pixs1. The result is pixs1 \ pixs2 = pixs1 & (~pixs2) (3) There are 4 cases: (a) pixd == null, (src1 - src2) --> new pixd (b) pixd == pixs1, (src1 - src2) --> src1 (in-place) (c) pixd == pixs2, (src1 - src2) --> src2 (in-place) (d) pixd != pixs1 && pixd != pixs2), (src1 - src2) --> input pixd (4) For clarity, if the case is known, use these patterns: (a) pixd = pixSubtract(NULL, pixs1, pixs2); (b) pixSubtract(pixs1, pixs1, pixs2); (c) pixSubtract(pixs2, pixs1, pixs2); (d) pixSubtract(pixd, pixs1, pixs2); (5) The size of the result is determined by pixs1. (6) The depths of pixs1 and pixs2 must be equal.
l_int32 pixThresholdPixelSum ( PIX *pix, l_int32 thresh, l_int32 *pabove, l_int32 *tab8 )
pixThresholdPixelSum() Input: pix (1 bpp) threshold &above (<return> 1 if above threshold; 0 if equal to or less than threshold) tab8 (<optional> 8-bit pixel lookup table) Return: 0 if OK; 1 on error Notes: (1) This sums the ON pixels and returns immediately if the count goes above threshold. It is therefore more efficient for matching images (by running this function on the xor of the 2 images) than using pixCountPixels(), which counts all pixels before returning.
NUMA * pixVarianceByColumn ( PIX *pix, BOX *box )
pixVarianceByColumn() Input: pix (8 or 16 bpp; no colormap) box (<optional> clipping box for variance; can be null) Return: na of rmsdev by column, or null on error Notes: (1) To resample for a bin size different from 1, use numaUniformSampling() on the result of this function. (2) We are actually computing the RMS deviation in each row. This is the square root of the variance.
NUMA * pixVarianceByRow ( PIX *pix, BOX *box )
pixVarianceByRow() Input: pix (8 or 16 bpp; no colormap) box (<optional> clipping box for variance; can be null) Return: na of rmsdev by row, or null on error Notes: (1) To resample for a bin size different from 1, use numaUniformSampling() on the result of this function. (2) We are actually computing the RMS deviation in each row. This is the square root of the variance.
l_int32 pixVarianceInRect ( PIX *pix, BOX *box, l_float32 *prootvar )
pixVarianceInRect() Input: pix (1, 2, 4, 8 bpp; not cmapped) box (<optional> if null, use entire image) &rootvar (<return> sqrt variance of pixel values in region) Return: 0 if OK; 1 on error
PIX * pixXor ( PIX *pixd, PIX *pixs1, PIX *pixs2 )
pixXor() Input: pixd (<optional>; this can be null, equal to pixs1, different from pixs1) pixs1 (can be == pixd) pixs2 (must be != pixd) Return: pixd always Notes: (1) This gives the XOR of two images with equal depth, aligning them to the the UL corner. pixs1 and pixs2 need not have the same width and height. (2) There are 3 cases: (a) pixd == null, (src1 ^ src2) --> new pixd (b) pixd == pixs1, (src1 ^ src2) --> src1 (in-place) (c) pixd != pixs1, (src1 ^ src2) --> input pixd (3) For clarity, if the case is known, use these patterns: (a) pixd = pixXor(NULL, pixs1, pixs2); (b) pixXor(pixs1, pixs1, pixs2); (c) pixXor(pixd, pixs1, pixs2); (4) The size of the result is determined by pixs1. (5) The depths of pixs1 and pixs2 must be equal. (6) Note carefully that the order of pixs1 and pixs2 only matters for the in-place case. For in-place, you must have pixd == pixs1. Setting pixd == pixs2 gives an incorrect result: the copy puts pixs1 image data in pixs2, and the rasterop is then between pixs2 and pixs2 (a no-op).
l_int32 pixZero ( PIX *pix, l_int32 *pempty )
pixZero() Input: pix (all depths; not colormapped) &empty (<return> 1 if all bits in image are 0; 0 otherwise) Return: 0 if OK; 1 on error Notes: (1) For a binary image, if there are no fg (black) pixels, empty = 1. (2) For a grayscale image, if all pixels are black (0), empty = 1. (3) For an RGB image, if all 4 components in every pixel is 0, empty = 1.
NUMA * pixaCountPixels ( PIXA *pixa )
pixaCountPixels() Input: pixa (array of 1 bpp pix) Return: na of ON pixels in each pix, or null on error
Zakariyya Mughal <zmughal@cpan.org>
This software is copyright (c) 2014 by Zakariyya Mughal.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
To install Image::Leptonica, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Image::Leptonica
CPAN shell
perl -MCPAN -e shell install Image::Leptonica
For more information on module installation, please visit the detailed CPAN module installation guide.