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/*
* Gray8VertTrapWarp.java
*
* Created on September 9, 2006, 3:17 PM
*
* 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 nColStart
* starting column of trapezoid in input image
* @param nColEnd
* bounding column of trapezoid in input image. This is one past
* the actual last column processed in the input image.
* @param nRowTopStart
* top edge of trapezoid in starting column.
* @param nRowBotStart
* bottom bound of trapezoid in starting column. This is one past
* the actual last row processed in the input image.
* @param nRowTopEnd
* top edge of trapezoid in ending column
* @param nRowBotEnd
* bottom bound of trapezoid in ending column. This is one past
* the actual last column processed in the input image. The
* column referred to as the ending row is the one above the
* bounding row, i.e., nColEnd.
* @throws ImageError
* if the trapezoid is empty or outside the bounds of any image,
* i.e., if nColStart < 0, or nColEnd ≤ nColStart, or
* nRowTopStart ≤ nRowBotStart, or nRowTopEnd ≤
* nRowBotEnd.
*/
public Gray8VertTrapWarp(final int nColStart, final int nColEnd, final int nRowTopStart, final int nRowBotStart, final int nRowTopEnd, final int nRowBotEnd) throws ImageError {
setTrapezoid(nColStart, nColEnd, nRowTopStart, nRowBotStart, nRowTopEnd, nRowBotEnd);
}
/**
* 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 nRowTopEnd;
}
/**
* 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 nRowTopStart;
}
/**
* 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 nRowBotEnd;
}
/**
* 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 nRowBotStart;
}
/**
* Returns the ending row of the trapezoid.
*
* @return the bottom row of the trapezoid.
*/
public int getRowEnd() {
return nColEnd;
}
/**
* Returns the starting row of the trapezoid.
*
* @return the top row of the trapezoid.
*/
public int getRowStart() {
return nColStart;
}
/**
* 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 ((nRowBotStart > image.getHeight()) || (nRowBotEnd > image.getHeight()) || (nColEnd > image.getWidth())) {
throw new ImageError(ImageError.PACKAGE.CORE, ErrorCodes.BOUNDS_OUTSIDE_IMAGE, image.toString(), toString(), null);
}
// we scale everything by 8 bits for accurate computation without
// floating point
int fTop = nRowTopStart << 8;
int fBot = nRowBotStart << 8;
final int nHeight = imageOutput.getHeight();
final int nWidth = imageOutput.getWidth();
final int fTopIncr = ((nRowTopEnd - nRowTopStart) << 8) / nWidth;
final int fBotIncr = ((nRowBotEnd - nRowBotStart) << 8) / nWidth;
final Byte[] in = ((Gray8Image) image).getData();
final Byte[] out = ((Gray8Image) super.imageOutput).getData();
for (int i = 0; i < nWidth; i++) {
// these are scaled by 8 bits
int fY = fTop;
final int fYIncr = (fBot - fTop) / nHeight;
for (int j = 0; j < nHeight; j++) {
// truncate scaled pixel position
final int iY = Math.min(image.getHeight() - 2, fY >> 8);
final int topPixel = in[i + nColStart + ((iY) * image.getWidth())];
final int botPixel = in[i + nColStart + ((iY + 1) * image.getWidth())];
// calculate fractional component of pixel between left and
// right
final int interp = (((botPixel - topPixel) * ((fY - (iY << 8)))) >> 8);
out[i + (j * nWidth)] = (byte) Math.max(Byte.MIN_VALUE, Math.min(Byte.MAX_VALUE, topPixel + interp));
fY += fYIncr;
}
fTop += fTopIncr;
fBot += fBotIncr;
}
super.setOutput(super.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 nColStart
* starting row of trapezoid in input image
* @param nColEnd
* ending row of trapezoid in input image
* @param nRowTopStart
* left edge of trapezoid on starting row.
* @param nRowBotStart
* right edge of trapezoid on starting row
* @param nRowTopEnd
* left edge of trapezoid on ending row
* @param nRowBotEnd
* right edge of trapezoid on ending row
* @throws ImageError
* if the trapezoid is empty or outside the bounds of any image,
* i.e., if nColStart < 0, or nColEnd ≤ nColStart, or
* nRowTopStart ≤ nRowBotStart, or nRowTopEnd ≤
* nRowBotEnd.
*/
public void setTrapezoid(final int nColStart, final int nColEnd, final int nRowTopStart, final int nRowBotStart, final int nRowTopEnd, final int nRowBotEnd) throws ImageError {
if ((nColStart >= nColEnd) || (nRowTopStart >= nRowBotStart) || (nRowTopEnd >= nRowBotEnd)) {
throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.PARAMETER_OUT_OF_RANGE, new Integer(nColStart).toString(), new Integer(nColEnd).toString(), null);
}
this.nColStart = nColStart;
this.nColEnd = nColEnd;
this.nRowTopStart = nRowTopStart;
this.nRowBotStart = nRowBotStart;
this.nRowTopEnd = nRowTopEnd;
this.nRowBotEnd = nRowBotEnd;
if ((this.nColStart < 0) || (this.nRowTopStart < 0) || (this.nRowBotStart < 0)) {
throw new ImageError(ImageError.PACKAGE.CORE, ErrorCodes.BOUNDS_OUTSIDE_IMAGE, toString(), null, null);
}
final int nWidth = this.nColEnd - this.nColStart;
final int nHeight = Math.max(this.nRowBotStart - this.nRowTopStart, this.nRowBotEnd - this.nRowTopEnd);
super.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.Gray8VertTrapWarpxxx
* (startRow,endRow,leftColStart,
* rightColStart,leftColEnd,rightColEnd)"
*/
@Override
public String toString() {
return super.toString() + " (" + nColStart + "," + //$NON-NLS-1$ //$NON-NLS-2$
nColEnd + "," + nRowTopStart + "," + //$NON-NLS-1$ //$NON-NLS-2$
nRowBotStart + "," + nRowTopEnd + "," + //$NON-NLS-1$ //$NON-NLS-2$
nRowBotEnd + ")"; //$NON-NLS-1$
}
}