content: /*
   * Copyright 2002-2019 Drew Noakes and contributors
   *
   *    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
   *
   *        https://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)));
      }
  }
  