/*
* Copyright 2002-2016 Drew Noakes
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* More information about this project is available at:
*
* https://drewnoakes.com/code/exif/
* https://github.com/drewnoakes/metadata-extractor
*/
package com.drew.imaging;
/**
* Contains helper methods that perform photographic conversions.
*
* @author Drew Noakes https://drewnoakes.com
*/
public final class PhotographicConversions
{
public final static double ROOT_TWO = Math.sqrt(2);
private PhotographicConversions() throws Exception
{
throw new Exception("Not intended for instantiation.");
}
/**
* Converts an aperture value to its corresponding F-stop number.
*
* @param aperture the aperture value to convert
* @return the F-stop number of the specified aperture
*/
public static double apertureToFStop(double aperture)
{
return Math.pow(ROOT_TWO, aperture);
// NOTE jhead uses a different calculation as far as i can tell... this confuses me...
// fStop = (float)Math.exp(aperture * Math.log(2) * 0.5));
}
/**
* Converts a shutter speed to an exposure time.
*
* @param shutterSpeed the shutter speed to convert
* @return the exposure time of the specified shutter speed
*/
public static double shutterSpeedToExposureTime(double shutterSpeed)
{
return (float) (1 / Math.exp(shutterSpeed * Math.log(2)));
}
}