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Leptonica 1.68
C Image Processing Library
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Leptonica 1.68
C Image Processing Library
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Image enhancements: gamma TRC mapping; contrast enhancement, histogram eq; unsharp-masking; hue and saturation. More...
Go to the source code of this file.
Image enhancements: gamma TRC mapping; contrast enhancement, histogram eq; unsharp-masking; hue and saturation.
Gamma TRC (tone reproduction curve) mapping
PIX *pixGammaTRC()
PIX *pixGammaTRCMasked()
PIX *pixGammaTRCWithAlpha()
NUMA *numaGammaTRC()
Contrast enhancement
PIX *pixContrastTRC()
PIX *pixContrastTRCMasked()
NUMA *numaContrastTRC()
Histogram equalization
PIX *pixEqualizeTRC()
NUMA *numaEqualizeTRC()
Generic TRC mapper
PIX *pixTRCMap()
Unsharp-masking
PIX *pixUnsharpMasking()
PIX *pixUnsharpMaskingGray()
PIX *pixUnsharpMaskingFast()
PIX *pixUnsharpMaskingGrayFast()
PIX *pixUnsharpMaskingGray1D()
PIX *pixUnsharpMaskingGray2D()
Hue and saturation modification
PIX *pixModifyHue()
PIX *pixModifySaturation()
l_int32 pixMeasureSaturation()
General multiplicative constant color transform
PIX *pixMultConstantColor()
PIX *pixMultMatrixColor()
Edge by bandpass
PIX *pixHalfEdgeByBandpass()
Gamma correction, contrast enhancement and histogram equalization
apply a simple mapping function to each pixel (or, for color
images, to each sample (i.e., r,g,b) of the pixel).
- Gamma correction either lightens the image or darkens
it, depending on whether the gamma factor is greater
or less than 1.0, respectively.
- Contrast enhancement darkens the pixels that are already
darker than the middle of the dynamic range (128)
and lightens pixels that are lighter than 128.
- Histogram equalization remaps to have the same number
of image pixels at each of 256 intensity values. This is
a quick and dirty method of adjusting contrast and brightness
to bring out details in both light and dark regions.
Unsharp masking is a more complicated enhancement.
A "high frequency" image, generated by subtracting
the smoothed ("low frequency") part of the image from
itself, has all the energy at the edges. This "edge image"
has 0 average value. A fraction of the edge image is
then added to the original, enhancing the differences
between pixel values at edges. Because we represent
images as l_uint8 arrays, we preserve dynamic range and
handle negative values by doing all the arithmetic on
shifted l_uint16 arrays; the l_uint8 values are recovered
at the end.
Hue and saturation modification work in HSV space. Because
this is too large for efficient table lookup, each pixel value
is transformed to HSV, modified, and transformed back.
It's not the fastest way to do this, but the method is
easily understood.
Unsharp masking is never in-place, and returns a clone if no
operation is to be performed.
Definition in file enhance.c.
Input: pixd (<optional> null or equal to pixs) pixs (8 or 32 bpp; or 2, 4 or 8 bpp with colormap) gamma (gamma correction; must be > 0.0) minval (input value that gives 0 for output; can be < 0) maxval (input value that gives 255 for output; can be > 255) Return: pixd always
Notes: (1) pixd must either be null or equal to pixs. For in-place operation, set pixd == pixs: pixGammaTRC(pixs, pixs, ...); To get a new image, set pixd == null: pixd = pixGammaTRC(NULL, pixs, ...); (2) If pixs is colormapped, the colormap is transformed, either in-place or in a copy of pixs. (3) We use a gamma mapping between minval and maxval. (4) If gamma < 1.0, the image will appear darker; if gamma > 1.0, the image will appear lighter; (5) If gamma = 1.0 and minval = 0 and maxval = 255, no enhancement is performed; return a copy unless in-place, in which case this is a no-op. (6) For color images that are not colormapped, the mapping is applied to each component. (7) minval and maxval are not restricted to the interval [0, 255]. If minval < 0, an input value of 0 is mapped to a nonzero output. This will turn black to gray. If maxval > 255, an input value of 255 is mapped to an output value less than 255. This will turn white (e.g., in the background) to gray. (8) Increasing minval darkens the image. (9) Decreasing maxval bleaches the image. (10) Simultaneously increasing minval and decreasing maxval will darken the image and make the colors more intense; e.g., minval = 50, maxval = 200. (11) See numaGammaTRC() for further examples of use.
Definition at line 153 of file enhance.c.
References ERROR_PTR, L_WARNING, NULL, numaDestroy(), numaGammaTRC(), pixcmapGammaTRC(), pixCopy(), L_Dewarp::pixd, pixGetColormap(), pixGetDepth(), pixTRCMap(), and PROCNAME.
Referenced by main(), pixGammaTRCMasked(), and pixThresholdSpreadNorm().
| PIX* pixGammaTRCMasked | ( | PIX * | pixd, |
| PIX * | pixs, | ||
| PIX * | pixm, | ||
| l_float32 | gamma, | ||
| l_int32 | minval, | ||
| l_int32 | maxval | ||
| ) |
Input: pixd (<optional> null or equal to pixs) pixs (8 or 32 bpp; not colormapped) pixm (<optional> null or 1 bpp) gamma (gamma correction; must be > 0.0) minval (input value that gives 0 for output; can be < 0) maxval (input value that gives 255 for output; can be > 255) Return: pixd always
Notes: (1) Same as pixGammaTRC() except mapping is optionally over a subset of pixels described by pixm. (2) Masking does not work for colormapped images. (3) See pixGammaTRC() for details on how to use the parameters.
Definition at line 219 of file enhance.c.
References ERROR_PTR, L_WARNING, NULL, numaDestroy(), numaGammaTRC(), pixCopy(), L_Dewarp::pixd, pixGammaTRC(), pixGetColormap(), pixGetDepth(), pixTRCMap(), and PROCNAME.
Referenced by main().
| PIX* pixGammaTRCWithAlpha | ( | PIX * | pixd, |
| PIX * | pixs, | ||
| l_float32 | gamma, | ||
| l_int32 | minval, | ||
| l_int32 | maxval | ||
| ) |
Input: pixd (<optional> null or equal to pixs) pixs (32 bpp) gamma (gamma correction; must be > 0.0) minval (input value that gives 0 for output; can be < 0) maxval (input value that gives 255 for output; can be > 255) Return: pixd always
Notes: (1) See usage notes in pixGammaTRC(). (2) This version saves the alpha channel. It is only valid for 32 bpp (no colormap), and is a bit slower.
Definition at line 281 of file enhance.c.
References ERROR_PTR, L_ALPHA_CHANNEL, L_WARNING, NULL, numaDestroy(), numaGammaTRC(), pixCopy(), L_Dewarp::pixd, pixDestroy(), pixGetDepth(), pixGetRGBComponent(), pixSetRGBComponent(), pixTRCMap(), and PROCNAME.
Referenced by pixAffinePtaGammaXform(), pixBilinearPtaGammaXform(), pixProjectivePtaGammaXform(), pixRotateGammaXform(), and pixScaleGammaXform().
Input: gamma (gamma factor; must be > 0.0) minval (input value that gives 0 for output) maxval (input value that gives 255 for output) Return: na, or null on error
Notes: (1) The map is returned as a numa; values are clipped to [0, 255]. (2) To force all intensities into a range within fraction delta of white, use: minval = -256 * (1 - delta) / delta maxval = 255 (3) To force all intensities into a range within fraction delta of black, use: minval = 0 maxval = 256 * (1 - delta) / delta
Definition at line 339 of file enhance.c.
References ERROR_PTR, L_MAX, L_MIN, L_WARNING, NULL, numaAddNumber(), numaCreate(), and PROCNAME.
Referenced by main(), pixcmapGammaTRC(), pixColorContent(), pixColorMagnitude(), pixGammaTRC(), pixGammaTRCMasked(), pixGammaTRCWithAlpha(), and pixGlobalNormRGB().
Input: pixd (<optional> null or equal to pixs) pixs (8 or 32 bpp; or 2, 4 or 8 bpp with colormap) factor (0.0 is no enhancement) Return: pixd always
Notes: (1) pixd must either be null or equal to pixs. For in-place operation, set pixd == pixs: pixContrastTRC(pixs, pixs, ...); To get a new image, set pixd == null: pixd = pixContrastTRC(NULL, pixs, ...); (2) If pixs is colormapped, the colormap is transformed, either in-place or in a copy of pixs. (3) Contrast is enhanced by mapping each color component using an atan function with maximum slope at 127. Pixels below 127 are lowered in intensity and pixels above 127 are increased. (4) The useful range for the contrast factor is scaled to be in (0.0 to 1.0), but larger values can also be used. (5) If factor == 0.0, no enhancement is performed; return a copy unless in-place, in which case this is a no-op. (6) For color images that are not colormapped, the mapping is applied to each component.
Definition at line 407 of file enhance.c.
References ERROR_PTR, L_WARNING, NULL, numaContrastTRC(), numaDestroy(), pixcmapContrastTRC(), pixCopy(), L_Dewarp::pixd, pixGetColormap(), pixGetDepth(), pixTRCMap(), and PROCNAME.
Referenced by main(), and pixContrastTRCMasked().
Input: pixd (<optional> null or equal to pixs) pixs (8 or 32 bpp; or 2, 4 or 8 bpp with colormap) pixm (<optional> null or 1 bpp) factor (0.0 is no enhancement) Return: pixd always
Notes: (1) Same as pixContrastTRC() except mapping is optionally over a subset of pixels described by pixm. (2) Masking does not work for colormapped images. (3) See pixContrastTRC() for details on how to use the parameters.
Definition at line 467 of file enhance.c.
References ERROR_PTR, L_WARNING, NULL, numaContrastTRC(), numaDestroy(), pixContrastTRC(), pixCopy(), L_Dewarp::pixd, pixGetColormap(), pixGetDepth(), pixTRCMap(), and PROCNAME.
Input: factor (generally between 0.0 (no enhancement) and 1.0, but can be larger than 1.0) Return: na, or null on error
Notes: (1) The mapping is monotonic increasing, where 0 is mapped to 0 and 255 is mapped to 255. (2) As 'factor' is increased from 0.0 (where the mapping is linear), the map gets closer to its limit as a step function that jumps from 0 to 255 at the center (input value = 127).
Definition at line 524 of file enhance.c.
References ENHANCE_SCALE_FACTOR, L_WARNING, numaAddNumber(), numaCreate(), numaMakeSequence(), and PROCNAME.
Referenced by main(), pixcmapContrastTRC(), pixContrastTRC(), and pixContrastTRCMasked().
Input: pixd (<optional> null or equal to pixs) pixs (8 bpp gray, 32 bpp rgb, or colormapped) fract (fraction of equalization movement of pixel values) factor (subsampling factor; integer >= 1) Return: pixd, or null on error
Notes: (1) pixd must either be null or equal to pixs. For in-place operation, set pixd == pixs: pixEqualizeTRC(pixs, pixs, ...); To get a new image, set pixd == null: pixd = pixEqualizeTRC(NULL, pixs, ...); (2) In histogram equalization, a tone reproduction curve mapping is used to make the number of pixels at each intensity equal. (3) If fract == 0.0, no equalization is performed; return a copy unless in-place, in which case this is a no-op. If fract == 1.0, equalization is complete. (4) Set the subsampling factor > 1 to reduce the amount of computation. (5) If pixs is colormapped, the colormap is removed and converted to rgb or grayscale. (6) If pixs has color, equalization is done in each channel separately. (7) Note that even if there is a colormap, we can get an in-place operation because the intermediate image pixt is copied back to pixs (which for in-place is the same as pixd).
Definition at line 591 of file enhance.c.
References COLOR_BLUE, COLOR_GREEN, COLOR_RED, ERROR_PTR, NULL, numaDestroy(), numaEqualizeTRC(), pixClone(), pixCopy(), L_Dewarp::pixd, pixDestroy(), pixGetColormap(), pixGetDepth(), pixGetRGBComponent(), pixRemoveColormap(), pixSetRGBComponent(), pixTRCMap(), PROCNAME, and REMOVE_CMAP_BASED_ON_SRC.
Input: pix (8 bpp, no colormap) fract (fraction of equalization movement of pixel values) factor (subsampling factor; integer >= 1) Return: nad, or null on error
Notes: (1) If fract == 0.0, no equalization will be performed. If fract == 1.0, equalization is complete. (2) Set the subsampling factor > 1 to reduce the amount of computation. (3) The map is returned as a numa with 256 values, specifying the equalized value (array value) for every input value (the array index).
Definition at line 677 of file enhance.c.
References ERROR_PTR, L_MIN, L_WARNING, NULL, numaAddNumber(), numaCreate(), numaDestroy(), numaGetFValue(), numaGetPartialSums(), numaGetSum(), pixGetDepth(), pixGetGrayHistogram(), and PROCNAME.
Referenced by pixEqualizeTRC().
Input: pixs (8 grayscale or 32 bpp rgb; not colormapped) pixm (<optional> 1 bpp mask) na (mapping array) Return: pixd, or null on error
Notes: (1) This operation is in-place on pixs. (2) For 32 bpp, this applies the same map to each of the r,g,b components. (3) The mapping array is of size 256, and it maps the input index into values in the range [0, 255]. (4) If defined, the optional 1 bpp mask pixm has its origin aligned with pixs, and the map function is applied only to pixels in pixs under the fg of pixm. (5) For 32 bpp, this does not save the alpha channel.
Definition at line 742 of file enhance.c.
References ERROR_INT, FREE, GET_DATA_BIT, GET_DATA_BYTE, L_BLUE_SHIFT, L_GREEN_SHIFT, L_RED_SHIFT, NULL, numaGetCount(), numaGetIArray(), pixGetColormap(), pixGetData(), pixGetDepth(), pixGetDimensions(), pixGetWpl(), PROCNAME, and SET_DATA_BYTE.
Referenced by pixContrastTRC(), pixContrastTRCMasked(), pixEqualizeTRC(), pixGammaTRC(), pixGammaTRCMasked(), and pixGammaTRCWithAlpha().
Input: pixs (all depths except 1 bpp; with or without colormaps) halfwidth ("half-width" of smoothing filter) fract (fraction of edge added back into image) Return: pixd, or null on error
Notes: (1) We use symmetric smoothing filters of odd dimension, typically use sizes of 3, 5, 7, etc. The parameter for these is (size - 1)/2; i.e., 1, 2, 3, etc. (2) The fract parameter is typically taken in the range: 0.2 < fract < 0.7 (3) Returns a clone if no sharpening is requested.
Definition at line 866 of file enhance.c.
References COLOR_BLUE, COLOR_GREEN, COLOR_RED, ERROR_PTR, L_BOTH_DIRECTIONS, L_WARNING, NULL, pixClone(), pixConvertTo8Or32(), pixCreateRGBImage(), L_Dewarp::pixd, pixDestroy(), pixGetDepth(), pixGetRGBComponent(), pixUnsharpMaskingFast(), pixUnsharpMaskingGray(), and PROCNAME.
Referenced by main(), pixRotateBinaryNice(), and pixScaleGeneral().
Input: pixs (8 bpp; no colormap) halfwidth ("half-width" of smoothing filter) fract (fraction of edge added back into image) Return: pixd, or null on error
Notes: (1) We use symmetric smoothing filters of odd dimension, typically use sizes of 3, 5, 7, etc. The parameter for these is (size - 1)/2; i.e., 1, 2, 3, etc. (2) The fract parameter is typically taken in the range: 0.2 < fract < 0.7 (3) Returns a clone if no sharpening is requested.
Definition at line 931 of file enhance.c.
References ERROR_PTR, L_BOTH_DIRECTIONS, L_WARNING, NULL, pixaccAdd(), pixaccCreate(), pixaccDestroy(), pixaccFinal(), pixaccMultConst(), pixaccSubtract(), pixBlockconvGray(), pixClone(), L_Dewarp::pixd, pixDestroy(), pixGetColormap(), pixGetDimensions(), pixUnsharpMaskingGrayFast(), and PROCNAME.
Referenced by pixUnsharpMasking().
Input: pixs (all depths except 1 bpp; with or without colormaps) halfwidth ("half-width" of smoothing filter; 1 and 2 only) fract (fraction of high frequency added to image) direction (L_HORIZ, L_VERT, L_BOTH_DIRECTIONS) Return: pixd, or null on error
Notes: (1) The fast version uses separable 1-D filters directly on the input image. The halfwidth is either 1 (full width = 3) or 2 (full width = 5). (2) The fract parameter is typically taken in the range: 0.2 < fract < 0.7 (3) To skip horizontal sharpening, use = 0.0; ditto for (4) For one dimensional filtering (as an example): For = 1, the low-pass filter is L: 1/3 1/3 1/3 and the high-pass filter is H = I - L: -1/3 2/3 -1/3 For = 2, the low-pass filter is L: 1/5 1/5 1/5 1/5 1/5 and the high-pass filter is H = I - L: -1/5 -1/5 4/5 -1/5 -1/5 The new sharpened pixel value is found by adding some fraction of the high-pass filter value (which sums to 0) to the initial pixel value: N = I + fract * H (5) For 2D, the sharpening filter is not separable, because the vertical filter depends on the horizontal location relative to the filter origin, and v.v. So we either do the full 2D filter (for == 1) or do the low-pass convolution separably and then compose with the original pix. (6) Returns a clone if no sharpening is requested.
Definition at line 1026 of file enhance.c.
References COLOR_BLUE, COLOR_GREEN, COLOR_RED, ERROR_PTR, L_BOTH_DIRECTIONS, L_HORIZ, L_VERT, L_WARNING, NULL, pixClone(), pixConvertTo8Or32(), pixCreateRGBImage(), L_Dewarp::pixd, pixDestroy(), pixGetDepth(), pixGetRGBComponent(), pixUnsharpMaskingGrayFast(), and PROCNAME.
Referenced by pixUnsharpMasking().
| PIX* pixUnsharpMaskingGrayFast | ( | PIX * | pixs, |
| l_int32 | halfwidth, | ||
| l_float32 | fract, | ||
| l_int32 | direction | ||
| ) |
Input: pixs (8 bpp; no colormap) halfwidth ("half-width" of smoothing filter: 1 or 2) fract (fraction of high frequency added to image) direction (L_HORIZ, L_VERT, L_BOTH_DIRECTIONS) Return: pixd, or null on error
Notes: (1) For usage and explanation of the algorithm, see notes in pixUnsharpMaskingFast(). (2) Returns a clone if no sharpening is requested.
Definition at line 1093 of file enhance.c.
References ERROR_PTR, L_BOTH_DIRECTIONS, L_HORIZ, L_VERT, L_WARNING, NULL, pixClone(), L_Dewarp::pixd, pixGetColormap(), pixGetDepth(), pixUnsharpMaskingGray1D(), pixUnsharpMaskingGray2D(), and PROCNAME.
Referenced by pixUnsharpMaskingFast(), and pixUnsharpMaskingGray().
Input: pixs (8 bpp; no colormap) halfwidth ("half-width" of smoothing filter: 1 or 2) fract (fraction of high frequency added to image) direction (of filtering; use L_HORIZ or L_VERT) Return: pixd, or null on error
Notes: (1) For usage and explanation of the algorithm, see notes in pixUnsharpMaskingFast(). (2) Returns a clone if no sharpening is requested.
Definition at line 1140 of file enhance.c.
References ERROR_PTR, GET_DATA_BYTE, L_HORIZ, L_MAX, L_MIN, L_WARNING, NULL, pixClone(), pixCopyBorder(), L_Dewarp::pixd, pixGetColormap(), pixGetData(), pixGetDimensions(), pixGetWpl(), PROCNAME, and SET_DATA_BYTE.
Referenced by pixUnsharpMaskingGrayFast().
Input: pixs (8 bpp; no colormap) halfwidth ("half-width" of smoothing filter: 1 or 2) fract (fraction of high frequency added to image) Return: pixd, or null on error
Notes: (1) For halfwidth == 1, we implement the full sharpening filter directly. For halfwidth == 2, we implement the the lowpass filter separably and then compute the sharpening result locally. (2) Returns a clone if no sharpening is requested.
Definition at line 1277 of file enhance.c.
References ERROR_PTR, fpixCreate(), fpixDestroy(), fpixGetData(), fpixGetWpl(), GET_DATA_BYTE, L_MAX, L_MIN, L_WARNING, NULL, pixClone(), pixCopyBorder(), L_Dewarp::pixd, pixGetColormap(), pixGetData(), pixGetDimensions(), pixGetWpl(), PROCNAME, and SET_DATA_BYTE.
Referenced by pixUnsharpMaskingGrayFast().
Input: pixd (<optional> can be null or equal to pixs) pixs (32 bpp rgb) fract (between -1.0 and 1.0) Return: pixd, or null on error
Notes: (1) pixd must either be null or equal to pixs. For in-place operation, set pixd == pixs: pixEqualizeTRC(pixs, pixs, ...); To get a new image, set pixd == null: pixd = pixEqualizeTRC(NULL, pixs, ...); (1) Use fract > 0.0 to increase hue value; < 0.0 to decrease it. 1.0 (or -1.0) represents a 360 degree rotation; i.e., no change. (2) If no modification is requested (fract = -1.0 or 0 or 1.0), return a copy unless in-place, in which case this is a no-op.
Definition at line 1412 of file enhance.c.
References composeRGBPixel(), convertHSVToRGB(), convertRGBToHSV(), ERROR_PTR, extractRGBValues(), L_ABS, L_WARNING, NULL, pixCopy(), L_Dewarp::pixd, pixGetColormap(), pixGetData(), pixGetDimensions(), pixGetWpl(), and PROCNAME.
Referenced by main().
Input: pixd (<optional> can be null, existing or equal to pixs) pixs (32 bpp rgb) fract (between -1.0 and 1.0) Return: pixd, or null on error
Notes: (1) If fract > 0.0, it gives the fraction that the pixel saturation is moved from its initial value toward 255. If fract < 0.0, it gives the fraction that the pixel saturation is moved from its initial value toward 0. The limiting values for fract = -1.0 (1.0) thus set the saturation to 0 (255). (2) If fract = 0, no modification is requested; return a copy unless in-place, in which case this is a no-op.
Definition at line 1480 of file enhance.c.
References composeRGBPixel(), convertHSVToRGB(), convertRGBToHSV(), ERROR_PTR, extractRGBValues(), L_ABS, L_WARNING, NULL, pixCopy(), L_Dewarp::pixd, pixGetData(), pixGetDimensions(), pixGetWpl(), and PROCNAME.
Referenced by main().
Input: pixs (32 bpp rgb) factor (subsampling factor; integer >= 1) &sat (<return> average saturation) Return: pixd, or null on error
Definition at line 1533 of file enhance.c.
References convertRGBToHSV(), ERROR_INT, extractRGBValues(), pixGetData(), pixGetDimensions(), pixGetWpl(), and PROCNAME.
Referenced by main().
Definition at line 1590 of file enhance.c.
References composeRGBPixel(), ERROR_PTR, extractRGBValues(), L_MAX, L_MIN, NULL, pixcmapGetColor(), pixcmapGetCount(), pixcmapResetColor(), pixCopy(), pixCreateTemplateNoInit(), L_Dewarp::pixd, pixGetColormap(), pixGetData(), pixGetDimensions(), pixGetWpl(), and PROCNAME.
Referenced by main().
Definition at line 1690 of file enhance.c.
References composeRGBPixel(), ERROR_PTR, extractRGBValues(), kernelGetElement(), kernelGetParameters(), L_MAX, L_MIN, NULL, pixcmapGetColor(), pixcmapGetCount(), pixcmapResetColor(), pixCopy(), pixCreateTemplateNoInit(), L_Dewarp::pixd, pixGetColormap(), pixGetData(), pixGetDimensions(), pixGetWpl(), and PROCNAME.
Referenced by main().
Input: pixs (8 bpp gray or 32 bpp rgb) sm1h, sm1v ("half-widths" of smoothing filter sm1) sm2h, sm2v ("half-widths" of smoothing filter sm2) (require sm2 != sm1) Return: pixd, or null on error
Notes: (1) We use symmetric smoothing filters of odd dimension, typically use 3, 5, 7, etc. The smoothing parameters for these are 1, 2, 3, etc. The filter size is related to the smoothing parameter by size = 2 * smoothing + 1 (2) Because we take the difference of two lowpass filters, this is actually a bandpass filter. (3) We allow both filters to be anisotropic. (4) Consider either the h or v component of the 2 filters. Depending on whether sm1 > sm2 or sm2 > sm1, we get different halves of the smoothed gradients (or "edges"). This difference of smoothed signals looks more like a second derivative of a transition, which we rectify by not allowing the signal to go below zero. If sm1 < sm2, the sm2 transition is broader, so the difference between sm1 and sm2 signals is positive on the upper half of the transition. Likewise, if sm1 > sm2, the sm1 - sm2 signal difference is positive on the lower half of the transition.
Definition at line 1797 of file enhance.c.
References ERROR_PTR, NULL, pixBlockconvAccum(), pixBlockconvGray(), pixClone(), pixConvertRGBToLuminance(), pixDestroy(), pixGetDepth(), pixSubtractGray(), and PROCNAME.
Referenced by main().
const l_float32 ENHANCE_SCALE_FACTOR = 5. [static] |
Definition at line 104 of file enhance.c.
Referenced by numaContrastTRC().
const l_int32 DEFAULT_HISTO_SAMPLES = 100000 [static] |
1.7.3