/*
* 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 <http://www.gnu.org/licenses/>.
*
*/
package jjil.algorithm;
import jjil.core.Error;
import jjil.core.Gray8Image;
import jjil.core.Image;
import jjil.core.PipelineStage;
/**
* This PipelineStage warps a trapezoid in the input gray image into a
* rectangular output image. The trapezoid is alined vertically, i.e., the
* vertical edges are parallel
* @author webb
*/
public class Gray8VertTrapWarp extends PipelineStage {
private int nRowTopEnd;
private int nRowTopStart;
private int nRowBotEnd;
private int nRowBotStart;
private int nColEnd;
private int nColStart;
/** Creates a new instance of Gray8VertTrapWarp. Gray8VertTrapWarp warps a trapezoidal
* region in an input gray image into a rectangular output image. The
* left and right sides of the trapezoid are aligned with the columns of the image.
* <p>
* 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 jjil.core.Error 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(
int nColStart,
int nColEnd,
int nRowTopStart,
int nRowBotStart,
int nRowTopEnd,
int nRowBotEnd) throws jjil.core.Error {
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 this.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 this.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 this.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 this.nRowBotStart;
}
/** Returns the ending row of the trapezoid.
*
* @return the bottom row of the trapezoid.
*/
public int getRowEnd() {
return this.nColEnd;
}
/** Returns the starting row of the trapezoid.
*
* @return the top row of the trapezoid.
*/
public int getRowStart() {
return this.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 jjil.core.Error if the input image is not gray,
* or the trapezoid already specified extends outside its bounds.
*/
public void push(Image image) throws jjil.core.Error {
if (!(image instanceof Gray8Image)) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.IMAGE_NOT_GRAY8IMAGE,
image.toString(),
null,
null);
}
if (this.nRowBotStart > image.getHeight() ||
this.nRowBotEnd > image.getHeight() ||
this.nColEnd > image.getWidth()) {
throw new Error(
Error.PACKAGE.CORE,
jjil.core.ErrorCodes.BOUNDS_OUTSIDE_IMAGE,
image.toString(),
this.toString(),
null);
}
// we scale everything by 8 bits for accurate computation without
// floating point
int fTop = this.nRowTopStart << 8;
int fBot = this.nRowBotStart << 8;
int nHeight = imageOutput.getHeight();
int nWidth = imageOutput.getWidth();
int fTopIncr = ((this.nRowTopEnd - this.nRowTopStart) << 8) / nWidth;
int fBotIncr = ((this.nRowBotEnd - this.nRowBotStart) << 8) / nWidth;
byte[] in = ((Gray8Image) image).getData();
byte[] out = ((Gray8Image)super.imageOutput).getData();
for (int i=0; i<nWidth; i++) {
// these are scaled by 8 bits
int fY = fTop;
int fYIncr = (fBot - fTop) / nHeight;
for (int j=0; j<nHeight; j++) {
// truncate scaled pixel position
int iY = Math.min(image.getHeight() - 2, fY >> 8);
int topPixel = in[i+this.nColStart+(iY)*image.getWidth()];
int botPixel = in[i+this.nColStart+(iY+1)*image.getWidth()];
// calculate fractional component of pixel between left and right
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 jjil.core.Error 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(
int nColStart,
int nColEnd,
int nRowTopStart,
int nRowBotStart,
int nRowTopEnd,
int nRowBotEnd) throws jjil.core.Error {
if (nColStart >= nColEnd ||
nRowTopStart >= nRowBotStart ||
nRowTopEnd >= nRowBotEnd) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.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 Error(
Error.PACKAGE.CORE,
jjil.core.ErrorCodes.BOUNDS_OUTSIDE_IMAGE,
this.toString(),
null,
null);
}
int nWidth = this.nColEnd - this.nColStart;
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)"
*/
public String toString() {
return super.toString() + " (" + this.nColStart + "," + //$NON-NLS-1$ //$NON-NLS-2$
this.nColEnd + "," + this.nRowTopStart + "," + //$NON-NLS-1$ //$NON-NLS-2$
this.nRowBotStart + "," + this.nRowTopEnd + "," + //$NON-NLS-1$ //$NON-NLS-2$
this.nRowBotEnd + ")"; //$NON-NLS-1$
}
}