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finished? doxygen ccstruct/coutln.cpp
This commit is contained in:
Jim O'Regan
parent
b81c766e28
commit
40fc4154ab
@ -631,7 +631,7 @@ bool C_OUTLINE::IsLegallyNested() const {
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* On entry, *it must be an iterator pointing to this. If this gets deleted
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* then this is extracted from *it, so an iteration can continue.
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* @param min_size minimum size for outline
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* @parm it outline iterator
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* @param it outline iterator
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*/
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void C_OUTLINE::RemoveSmallRecursive(int min_size, C_OUTLINE_IT* it) {
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if (box.width() < min_size || box.height() < min_size) {
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@ -652,9 +652,11 @@ void C_OUTLINE::RemoveSmallRecursive(int min_size, C_OUTLINE_IT* it) {
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// on data from an 8-bit Pix, and assume that any input x and/or y are already
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// constrained to be legal Pix coordinates.
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// Helper computes the local 2-D gradient (dx, dy) from the 2x2 cell centered
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// on the given (x,y). If the cell would go outside the image, it is padded
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// with white.
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/**
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* Helper computes the local 2-D gradient (dx, dy) from the 2x2 cell centered
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* on the given (x,y). If the cell would go outside the image, it is padded
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* with white.
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*/
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static void ComputeGradient(const l_uint32* data, int wpl,
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int x, int y, int width, int height,
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ICOORD* gradient) {
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@ -671,9 +673,11 @@ static void ComputeGradient(const l_uint32* data, int wpl,
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gradient->set_y(pix_x_prevy + pix_prevx_prevy - (pix_x_y + pix_prevx_y));
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}
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// Helper evaluates a vertical difference, (x,y) - (x,y-1), returning true if
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// the difference, matches diff_sign and updating the best_diff, best_sum,
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// best_y if a new max.
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/**
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* Helper evaluates a vertical difference, (x,y) - (x,y-1), returning true if
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* the difference, matches diff_sign and updating the best_diff, best_sum,
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* best_y if a new max.
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*/
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static bool EvaluateVerticalDiff(const l_uint32* data, int wpl, int diff_sign,
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int x, int y, int height,
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int* best_diff, int* best_sum, int* best_y) {
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@ -691,9 +695,11 @@ static bool EvaluateVerticalDiff(const l_uint32* data, int wpl, int diff_sign,
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return diff > 0;
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}
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// Helper evaluates a horizontal difference, (x,y) - (x-1,y), where y is implied
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// by the input image line, returning true if the difference matches diff_sign
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// and updating the best_diff, best_sum, best_x if a new max.
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/**
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* Helper evaluates a horizontal difference, (x,y) - (x-1,y), where y is implied
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* by the input image line, returning true if the difference matches diff_sign
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* and updating the best_diff, best_sum, best_x if a new max.
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*/
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static bool EvaluateHorizontalDiff(const l_uint32* line, int diff_sign,
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int x, int width,
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int* best_diff, int* best_sum, int* best_x) {
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@ -710,17 +716,21 @@ static bool EvaluateHorizontalDiff(const l_uint32* line, int diff_sign,
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return diff > 0;
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}
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// Adds sub-pixel resolution EdgeOffsets for the outline if the supplied
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// pix is 8-bit. Does nothing otherwise.
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// Operation: Consider the following near-horizontal line:
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// _________
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// |________
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// |________
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// At *every* position along this line, the gradient direction will be close
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// to vertical. Extrapoaltion/interpolation of the position of the threshold
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// that was used to binarize the image gives a more precise vertical position
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// for each horizontal step, and the conflict in step direction and gradient
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// direction can be used to ignore the vertical steps.
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/**
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* Adds sub-pixel resolution EdgeOffsets for the outline if the supplied
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* pix is 8-bit. Does nothing otherwise.
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* Operation: Consider the following near-horizontal line:
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* @verbatim
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* _________
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* |________
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* |________
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* @endverbatim
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* At *every* position along this line, the gradient direction will be close
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* to vertical. Extrapoaltion/interpolation of the position of the threshold
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* that was used to binarize the image gives a more precise vertical position
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* for each horizontal step, and the conflict in step direction and gradient
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* direction can be used to ignore the vertical steps.
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*/
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void C_OUTLINE::ComputeEdgeOffsets(int threshold, Pix* pix) {
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if (pixGetDepth(pix) != 8) return;
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const l_uint32* data = pixGetData(pix);
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@ -809,30 +819,35 @@ void C_OUTLINE::ComputeEdgeOffsets(int threshold, Pix* pix) {
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}
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}
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// Adds sub-pixel resolution EdgeOffsets for the outline using only
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// a binary image source.
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// Runs a sliding window of 5 edge steps over the outline, maintaining a count
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// of the number of steps in each of the 4 directions in the window, and a
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// sum of the x or y position of each step (as appropriate to its direction.)
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// Ignores single-count steps EXCEPT the sharp U-turn and smoothes out the
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// perpendicular direction. Eg
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// ___ ___ Chain code from the left:
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// |___ ___ ___| 222122212223221232223000
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// |___| |_| Corresponding counts of each direction:
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// 0 00000000000000000123
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// 1 11121111001111100000
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// 2 44434443443333343321
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// 3 00000001111111112111
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// Count of direction at center 41434143413313143313
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// Step gets used? YNYYYNYYYNYYNYNYYYyY (y= U-turn exception)
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// Path redrawn showing only the used points:
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// ___ ___
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// ___ ___ ___|
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// ___ _
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// Sub-pixel edge position cannot be shown well with ASCII-art, but each
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// horizontal step's y position is the mean of the y positions of the steps
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// in the same direction in the sliding window, which makes a much smoother
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// outline, without losing important detail.
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/**
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* Adds sub-pixel resolution EdgeOffsets for the outline using only
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* a binary image source.
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*
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* Runs a sliding window of 5 edge steps over the outline, maintaining a count
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* of the number of steps in each of the 4 directions in the window, and a
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* sum of the x or y position of each step (as appropriate to its direction.)
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* Ignores single-count steps EXCEPT the sharp U-turn and smoothes out the
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* perpendicular direction. Eg
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* @verbatim
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* ___ ___ Chain code from the left:
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* |___ ___ ___| 222122212223221232223000
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* |___| |_| Corresponding counts of each direction:
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* 0 00000000000000000123
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* 1 11121111001111100000
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* 2 44434443443333343321
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* 3 00000001111111112111
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* Count of direction at center 41434143413313143313
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* Step gets used? YNYYYNYYYNYYNYNYYYyY (y= U-turn exception)
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* Path redrawn showing only the used points:
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* ___ ___
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* ___ ___ ___|
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* ___ _
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* @endverbatim
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* Sub-pixel edge position cannot be shown well with ASCII-art, but each
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* horizontal step's y position is the mean of the y positions of the steps
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* in the same direction in the sliding window, which makes a much smoother
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* outline, without losing important detail.
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*/
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void C_OUTLINE::ComputeBinaryOffsets() {
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delete [] offsets;
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offsets = new EdgeOffset[stepcount];
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@ -887,8 +902,10 @@ void C_OUTLINE::ComputeBinaryOffsets() {
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}
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}
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// Renders the outline to the given pix, with left and top being
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// the coords of the upper-left corner of the pix.
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/**
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* Renders the outline to the given pix, with left and top being
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* the coords of the upper-left corner of the pix.
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*/
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void C_OUTLINE::render(int left, int top, Pix* pix) const {
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ICOORD pos = start;
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for (int stepindex = 0; stepindex < stepcount; ++stepindex) {
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@ -965,8 +982,11 @@ void C_OUTLINE::plot(ScrollView* window,
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window->DrawTo(pos.x(), pos.y());
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}
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}
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// Draws the outline in the given colour, normalized using the given denorm,
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// making use of sub-pixel accurate information if available.
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/**
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* Draws the outline in the given colour, normalized using the given denorm,
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* making use of sub-pixel accurate information if available.
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*/
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void C_OUTLINE::plot_normed(const DENORM& denorm, ScrollView::Color colour,
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ScrollView* window) const {
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window->Pen(colour);
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@ -1025,10 +1045,12 @@ C_OUTLINE & C_OUTLINE::operator= (const C_OUTLINE & source) {
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return *this;
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}
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// Helper for ComputeBinaryOffsets. Increments pos, dir_counts, pos_totals
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// by the step, increment, and vertical step ? x : y position * increment
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// at step s Mod stepcount respectively. Used to add or subtract the
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// direction and position to/from accumulators of a small neighbourhood.
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/**
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* Helper for ComputeBinaryOffsets. Increments pos, dir_counts, pos_totals
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* by the step, increment, and vertical step ? x : y position * increment
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* at step s Mod stepcount respectively. Used to add or subtract the
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* direction and position to/from accumulators of a small neighbourhood.
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*/
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void C_OUTLINE::increment_step(int s, int increment, ICOORD* pos,
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int* dir_counts, int* pos_totals) const {
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int step_index = Modulo(s, stepcount);
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