LSSTApplications  18.0.0+106,18.0.0+50,19.0.0,19.0.0+1,19.0.0+10,19.0.0+11,19.0.0+13,19.0.0+17,19.0.0+2,19.0.0-1-g20d9b18+6,19.0.0-1-g425ff20,19.0.0-1-g5549ca4,19.0.0-1-g580fafe+6,19.0.0-1-g6fe20d0+1,19.0.0-1-g7011481+9,19.0.0-1-g8c57eb9+6,19.0.0-1-gb5175dc+11,19.0.0-1-gdc0e4a7+9,19.0.0-1-ge272bc4+6,19.0.0-1-ge3aa853,19.0.0-10-g448f008b,19.0.0-12-g6990b2c,19.0.0-2-g0d9f9cd+11,19.0.0-2-g3d9e4fb2+11,19.0.0-2-g5037de4,19.0.0-2-gb96a1c4+3,19.0.0-2-gd955cfd+15,19.0.0-3-g2d13df8,19.0.0-3-g6f3c7dc,19.0.0-4-g725f80e+11,19.0.0-4-ga671dab3b+1,19.0.0-4-gad373c5+3,19.0.0-5-ga2acb9c+2,19.0.0-5-gfe96e6c+2,w.2020.01
LSSTDataManagementBasePackage
image1.cc
/*
* LSST Data Management System
* Copyright 2008, 2009, 2010 LSST Corporation.
*
* This product includes software developed by the
* LSST Project (http://www.lsst.org/).
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the LSST License Statement and
* the GNU General Public License along with this program. If not,
* see <http://www.lsstcorp.org/LegalNotices/>.
*/
/*
* Image iterator tutorial.
*/
// Include the necessary headers;
// if using many image modules then you may prefer to include "lsst/afw/image.h"
#include "lsst/geom.h"
// Declare the desired Image type.
// Note: only specific types are supported; for the list of available types
// see the explicit instantiation code at the end of lsst/afw/image/src/Image.cc
typedef afwImage::Image<int> ImageT;
int main() {
// Declare an Image; its pixels are not yet initialized.
ImageT img(lsst::geom::Extent2I(10, 6));
// Initialize all pixels to a given value.
img = 100;
// Alternatively you can specify an initial value in the constructor:
ImageT img2(img.getDimensions(), 100.0);
// Here is a common and efficient way to set all pixels of the image.
// Note that the end condition is only computed once, for efficiency.
for (int y = 0; y != img.getHeight(); ++y) {
for (ImageT::x_iterator ptr = img.row_begin(y), end = img.row_end(y); ptr != end; ++ptr) {
*ptr = 100;
}
}
// It is probably slower to compute the end condition each time, as is done here.
for (int y = 0; y != img.getHeight(); ++y) {
for (ImageT::x_iterator ptr = img.row_begin(y); ptr != img.row_end(y); ++ptr) {
*ptr = 100;
}
}
// STL-compliant iterators are available.
// However, they are not very efficient because the image data may not be contiguous
// so these iterators must test for end-of-row on every increment.
// (By the way, we do guarantee that an image's row data is contiguous).
// iterator
for (ImageT::iterator ptr = img.begin(), end = img.end(); ptr != end; ++ptr) {
*ptr = 100;
}
// reverse_iterator
for (ImageT::reverse_iterator ptr = img.rbegin(), end = img.rend(); ptr != end; ++ptr) {
*ptr = 100;
}
// A different way of choosing begin() for use with (inefficient) iterator
for (ImageT::iterator ptr = img.at(0, 0), end = img.end(); ptr != end; ++ptr) {
*ptr = 100;
}
// There is one efficient STL-compliant iterator: "fast_iterator", but it only works for contiguous images
// (such as newly allocated images). If you attempt to use this on a subimage you will get an exception.
for (ImageT::fast_iterator ptr = img.begin(true), end = img.end(true); ptr != end; ++ptr) {
*ptr = 100;
}
// It is possible to traverse the image by columns instead of by rows,
// but because the data is row-contiguous, this has awful consequences upon cache performance.
for (int x = 0; x != img.getWidth(); ++x) {
for (ImageT::y_iterator ptr = img.col_begin(x), end = img.col_end(x); ptr != end; ++ptr) {
*ptr = 100;
}
}
// If you must traverse the image by columns then consider doing it in batches to improve
// cache performance, as shown here:
int x = 0;
for (; x != img.getWidth() % 4; ++x) {
for (ImageT::y_iterator ptr = img.col_begin(x), end = img.col_end(x); ptr != end; ++ptr) {
*ptr = 100;
}
}
for (; x != img.getWidth(); x += 4) {
for (ImageT::y_iterator ptr0 = img.col_begin(x + 0), end0 = img.col_end(x + 0),
ptr1 = img.col_begin(x + 1), ptr2 = img.col_begin(x + 2),
ptr3 = img.col_begin(x + 3);
ptr0 != end0; ++ptr0, ++ptr1, ++ptr2, ++ptr3) {
*ptr0 = *ptr1 = *ptr2 = *ptr3 = 100;
}
}
// Save the image to disk
img.writeFits("foo.fits");
return 0;
}