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/*
* Gray8TrapWarp.java
*
* Created on September 9, 2006, 3:17 PM
*
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
*
* Copyright 2007 by Jon A. Webb
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the Lesser GNU General Public License
* along with this program. If not, see
* The bounds are specified here in a manner consistent with the way they
* are specified as array bounds -- that is, the starting bound is closed
* (≤) and the ending bound is open (<).
*
* @param nRowStart
* starting row of trapezoid in input image
* @param nRowEnd
* bounding row of trapezoid in input image. This is one past the
* actual last row processed in the input image.
* @param nColLeftStart
* left edge of trapezoid on starting row.
* @param nColRightStart
* right bound of trapezoid on starting row. This is one past the
* actual last column processed in the input image.
* @param nColLeftEnd
* left edge of trapezoid on ending row
* @param nColRightEnd
* right bound of trapezoid on ending row. This is one past the
* actual last column processed in the input image. The row
* referred to as the ending row is the one above the bounding
* row, i.e., nRowEnd.
* @throws ImageError
* if the trapezoid is empty or outside the bounds of any image,
* i.e., if nRowStart < 0, or nRowEnd <= nRowStart, or
* nColLeftStart <= nColRightStart, or nColLeftEnd <=
* nColRightEnd.
*/
public Gray8TrapWarp(final int nRowStart, final int nRowEnd, final int nColLeftStart, final int nColRightStart, final int nColLeftEnd, final int nColRightEnd) throws ImageError {
setTrapezoid(nRowStart, nRowEnd, nColLeftStart, nColRightStart, nColLeftEnd, nColRightEnd);
}
/**
* Returns the left column position of the trapezoid in the ending row.
*
* @return the left edge position of the trapezoid in the ending row.
*/
public int getColLeftEnd() {
return nColLeftEnd;
}
/**
* Returns the left column position of the trapezoid in the starting row.
*
* @return the left edge position of the trapezoid in the starting row.
*/
public int getColLeftStart() {
return nColLeftStart;
}
/**
* Returns the right column position of the trapezoid in the ending row.
*
* @return the right edge position of the trapezoid in the ending row.
*/
public int getColRightEnd() {
return nColRightEnd;
}
/**
* Returns the right column position of the trapezoid in the starting row.
*
* @return the right edge position of the trapezoid in the starting row.
*/
public int getColRightStart() {
return nColRightStart;
}
/**
* Returns the ending row of the trapezoid.
*
* @return the bottom row of the trapezoid.
*/
public int getRowEnd() {
return nRowEnd;
}
/**
* Returns the starting row of the trapezoid.
*
* @return the top row of the trapezoid.
*/
public int getRowStart() {
return nRowStart;
}
/**
* Warps a trapezoidal region in the input gray image into a rectangular
* output image. Uses bilinear interpolation. The calculation of fractional
* image coordinates is done by multiplying all the coordinates by 256, to
* avoid floating point computation.
*
* @param image
* the input gray image.
* @throws ImageError
* if the input image is not gray, or the trapezoid already
* specified extends outside its bounds.
*/
@Override
public void push(final Image image) throws ImageError {
if (!(image instanceof Gray8Image)) {
throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.IMAGE_NOT_GRAY8IMAGE, image.toString(), null, null);
}
if ((nColRightStart > image.getWidth()) || (nColRightEnd > image.getWidth()) || (nRowEnd > image.getHeight())) {
throw new ImageError(ImageError.PACKAGE.CORE, ErrorCodes.BOUNDS_OUTSIDE_IMAGE, image.toString(), toString(), null);
}
int fLeft = (nColLeftStart * 256);
int fRight = (nColRightStart * 256);
final int nHeight = imageOutput.getHeight();
final int nWidth = imageOutput.getWidth();
final int fLeftIncr = ((nColLeftEnd - nColLeftStart) * 256) / nHeight;
final int fRightIncr = ((nColRightEnd - nColRightStart) * 256) / nHeight;
final Byte[] in = ((Gray8Image) image).getData();
final Byte[] out = imageOutput.getData();
for (int i = 0; i < nHeight; i++) {
// we scale everything by 8 bits for accurate computation without
// floating point
int fY = fLeft;
final int fYIncr = (fRight - fLeft) / nWidth;
for (int j = 0; j < nWidth; j++) {
final int iY = Math.min(image.getWidth() - 2, fY / 256);
// truncate floating-point pixel position
final int leftPixel = in[((i + nRowStart) * image.getWidth()) + iY];
final int rightPixel = in[((i + nRowStart) * image.getWidth()) + iY + 1];
// calculate fractional component of pixel between left and
// right
final int interp = ((rightPixel - leftPixel) * (fY - (iY * 256))) / 256;
out[(i * nWidth) + j] = (byte) (leftPixel + interp);
fY += fYIncr;
}
fLeft += fLeftIncr;
fRight += fRightIncr;
}
super.setOutput(imageOutput);
}
/**
* Sets the bounds of the trapezoid. Recreates the output image when they
* change. The output height is set to the input trapezoid height, and the
* output width is set to the larger of the trapezoid width at the first and
* last rows.
*
* @param nRowStart
* starting row of trapezoid in input image
* @param nRowEnd
* ending row of trapezoid in input image
* @param nColLeftStart
* left edge of trapezoid on starting row.
* @param nColRightStart
* right edge of trapezoid on starting row
* @param nColLeftEnd
* left edge of trapezoid on ending row
* @param nColRightEnd
* right edge of trapezoid on ending row
* @throws ImageError
* if the trapezoid is empty or outside the bounds of any image,
* i.e., if nRowStart < 0, or nRowEnd ≤ nRowStart, or
* nColLeftStart ≤ nColRightStart, or nColLeftEnd ≤
* nColRightEnd.
*/
public void setTrapezoid(final int nRowStart, final int nRowEnd, final int nColLeftStart, final int nColRightStart, final int nColLeftEnd, final int nColRightEnd) throws ImageError {
if (nRowStart >= nRowEnd) {
throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.WARP_START_ROW_GE_END_ROW, new Integer(nRowStart).toString(), new Integer(nRowEnd).toString(), null);
}
if (nColLeftStart >= nColRightStart) {
throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.WARP_START_LEFT_COL_GE_START_RIGHT_COL, new Integer(nColLeftStart).toString(),
new Integer(nColRightStart).toString(), null);
}
if (nColLeftEnd >= nColRightEnd) {
throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.WARP_END_LEFT_COL_GE_END_RIGHT_COL, new Integer(nColLeftEnd).toString(), new Integer(nColRightEnd).toString(), null);
}
this.nRowStart = nRowStart;
this.nRowEnd = nRowEnd;
this.nColLeftStart = nColLeftStart;
this.nColRightStart = nColRightStart;
this.nColLeftEnd = nColLeftEnd;
this.nColRightEnd = nColRightEnd;
if ((this.nRowStart < 0) || (this.nColLeftStart < 0) || (this.nColRightStart < 0)) {
throw new ImageError(ImageError.PACKAGE.CORE, ErrorCodes.BOUNDS_OUTSIDE_IMAGE, toString(), null, null);
}
final int nHeight = this.nRowEnd - this.nRowStart;
final int nWidth = Math.max(this.nColRightStart - this.nColLeftStart, this.nColRightEnd - this.nColLeftEnd);
imageOutput = new Gray8Image<>(nWidth, nHeight);
}
/**
* Returns a string describing the current instance. All the constructor
* parameters are returned in the order specified in the constructor.
*
* @return The string describing the current instance. The string is of the
* form "jjil.algorithm.Gray8TrapWarpxxx
* (startRow,endRow,leftColStart,
* rightColStart,leftColEnd,rightColEnd)"
*/
@Override
public String toString() {
return super.toString() + " (" + nRowStart + "," + //$NON-NLS-1$ //$NON-NLS-2$
nRowEnd + "," + nColLeftStart + "," + //$NON-NLS-1$ //$NON-NLS-2$
nColRightStart + "," + nColLeftEnd + "," + //$NON-NLS-1$ //$NON-NLS-2$
nColRightEnd + ")"; //$NON-NLS-1$
}
}