AdobeRGB to sRGB Filter

Version

The current version is AdobeRGB-to-sRGB-Filter 2.0 (11. December 2007).

Description

This is an album filter for JAlbum which converts images from the AdobeRGB color space in to the sRGB color space. This is important as JAlbum does not support the AdobeRGB color space and saves the images as if they were in sRGB since both profiles have the same annotation. This leads to a strong loss in saturation of the images. The AdobeRGB color space is often used by professional photographers as it can describe a bigger color spectrum compared to sRGB.  This is of an advantage for printing but unfortunately if is not suitable for web publishing as Safari is the only mainstream browser which natively supports AdobeRGB. All other browsers also show the images with less saturation.

Features

  • changes all images in a JAlbum album from the AdobeRGB color space to the sRGB color space
  • several caching mechanisms, to shorten the calculation precess

Warning

  • This filter will be applied to all images in you album. The filter does not check whether or not the image is actually in the AdobeRGB Color Space. All images are recalculated as if they were in the AdobeRGB Color Space. This might cause color problems in images which are not in using the AdobeRGB color space (usually over saturation). So only use this filter if you know what you are doing.
  • The calculation is very time intense. Long calculation times are normal when making an album.
  • The filter does not change the original images. So the images have to be recalculated every time when the album is generated again.
  • If the cache is not set correctly it can cause Java-Exceptions and the album will not be finished. See below for more information on how caching works.

Download

The entire filter package can be downloaded via the JAlbum Forum.

Installation and Usage

Unzip the content of the downloaded archive in the folder "/plugins" in your JAlbum installation (e.g. "C:/Program Files/JAlbum/").

How to apply the filter

  • Open an album of images in AdobeRGB you want to convert.
  • Open the Settings-Window.
  • Go to the section 'Advanced'.
  • Open the 'User Variables'-Tab.
  • Set the name of the first variable to 'filter1' and its value to 'class=AdobeRGBtosRGBFilter prescale=false'.
  • If you use any other filters on that album as well, make sure that they are applied after the AdobeRGBtosRGB-Filter. If any of those filters must be applied with prescale=true, you should change the AdobeRGBtosRGB-Filter also to prescale=true. I can not guarantee on how the images will look correctly if the AdobeRGBtosRGB-Filter is not the first filter. By changing its prescale value to true, the time to generate the album will increase dramatically. Don't be surprised if it takes several minutes for each image(!) to be generated if those are large images.

Caching

In Version 2.0 a caching mechanism was introduced to reduce the calculation time. You can choose between 4 levels of caching: 'none', 'low', 'normal' and 'high'. To set the caching just add e.g. 'caching=high' to the value of the filter variable. The default setting is 'normal'.
The cache saved the already calculated colors in pairs of original color and resulting color. The problem is, that up on a certain size it will throw a Java-OutOfMemoryError. The different levels say how often the cache is cleared to avoid this problem.
High-caching means that there is one cache for the entire album. This is the fasted but also the must vulnerable way of caching and it will break at large images and/or large albums.
Normal-caching means that the cache is cleared after every image. This will break only at large images.
Low-caching means that the cache is reset after every image and if the cache exceeds a certain size. The default size is 100 000 elements. This value can be changed by adding e.g. 'maxCacheSize=200000' to the value of the filter variable.
If the caching variable is set to 'none', no cache will be created. This is the safest and also the most time consuming way of generating your album. Small tip: take a short break and make yourself a cup of coffee or tea.

Version History

Version 1.0

  • Original version
  • changes all images of an album in the sRGB color space

Version 2.0

  • caching mechanism added


Ideas for future versions

  • better cache which is automatically reset as soon as it reaches a critical size
  • recognition if the current image is in the AdobeRGB color space and only then convert

Legal Issues

This filter uses the AdobeRGB1998.icc Color Profile provided by Adobe Systems Inc. By using this filter you agree to the Adobe Color Profile License Agreement. For further details see the file 'Adobe Color Profile License Agreement.pdf' which is included in the filter package.

Adobe is a registered Trademark of Adobe Systems Inc. For further details see the file 'Adobe Trademark Information.pdf' which is also included in the filter package.