PRODUCTS: J2K Escalator Documentation

Stellar Science presents J2K Escalator, an Adobe Photoshop File Format Plug-in that allows you to read JPEG 2000 imagery directly into Photoshop and other host image processing applications.

Normal Usage
J2K Escalator is a File Format plug-in that conforms to Adobe Photoshop's plug-in API. If you have an application that accepts these types of plug-ins then J2K Escalator will provide you with the ability to directly read in J2K imagery without performing offline file conversions. Examples of applications that support Adobe's File Format Plug-in API are:

  • Adobe Photoshop CS2/CS3/CS4(x86)
  • Adobe Photoshop Elements 5.0/6.0/7.0

Many other applications support Adobe's File Format Plug-in API. J2K Escalator has not been tested with every such application, but if your application supports Adobe's File Format Plug-in API, you are encouraged to download a free trial version of J2K Escalator to see if it will work with your application. Please let us know what you find.

Routine usage of J2K Escalator is very straightforward. Once the plug-in has been installed into a host application, you need only use the File|Open... capabilities provided by the host. In other words, you will be able to open J2K imagery files just as you would open a GIF image file. If your host application supports thumbnail display in its Open Dialog, then you will be able to see J2K thumbnails as well. Due to the complexity of the J2K format, however, it is not unusual for the appearance of a J2K thumbnail to differ somewhat from the way the image is initially displayed in your host application. If a J2K file is particularly large or has more than 3 channels, then J2K Escalator may be forced to make guesses as to the appropriate way to scale, crop, and channel map your image for the thumbnail display window. This is normal behavior. Once you have fully opened the image, you may use the capabilities provided by your host application to adjust the display parameters of the image.

Until you have purchased and entered a valid J2K license key for your host application, the first thing you will see after opening a J2K image file is the License Dialog:

This dialog will tell you how many more images you may load before your trial period is finished (Note: The number of trial image loads are fixed on a per-machine basis -- not a per host application basis). Once you have purchased a license key for your host application, you may enter it here and you will never have to see this window again. Your host application's key is displayed here because you will need it in order to purchase a corresponding J2K Escalator license key.

Press OK to clear this window. If you have entered a valid license key or you have trials remaining, your J2K image will usually begin loading immediately. In some instances, however, J2K Escalator will need to get more information from you before it can load the file.

Intensity Scaling
J2K Images can come in a variety of data types. J2K Escalator can handle nearly all of them, including images that contain the following pixel types:

  • 1 Bit Boolean
  • 8 Bit Unsigned Integer
  • 8 Bit Signed Integer
  • 16 Bit Unsigned Integer
  • 16 Bit Signed Integer

Unfortunately, the Adobe Photoshop API is not quite as flexible when it comes to data types. The API only supports 8 Bit Unsigned Integer, 16 Bit Unsigned Integer and 32 Bit Precision Real Numbers. When J2K Escalator encounters an image that is not one of these types, it will convert the image into an accepted type for you. This may require that the data be intensity scaled so that you will actually be able to see some relevant image detail. The following dialog will allow you to control the details of this transform if you wish:

Each pixel value in the J2K image will be multiplied by the specified Scale, added to the specified Bias and then clamped to the range of New Data Type where New Data Type is one of Photoshop's acceptable pixel types. J2K Escalator will sample the image and determine default values that will normally behave well. If you open an image, however, and it's all black or all white you may need to re-open the image and adjust these values accordingly.

Other Warnings
There are other types of J2K images that deserve special mention and J2K Escalator will point them out when it finds one. For example, you may see a warning box with one of the following messages when loading an image:

  • The selected image contains X channels. Photoshop only allows a maximum of 56 channels. J2K Escalator has truncated excess channels so that the image could be loaded - A single J2K image can contain an arbitrary number of channels whereas Photoshop will only handle 56 channel images. The current version of J2K Escalator handles this case by slicing off all channels past the 56th one. Future versions of the plug-in may allow the user more control over which channels they would like to view.
  • Photoshop seems to have a problem accepting 32 bit Multichannel images. To compensate for this issue, J2K Escalator is converting the image mode to XX. You can avoid this conversion by selecting a different bit depth - Empirically, we have found that Photoshop will not accept 32 bit multichannel images (it fails without offering a good reason). J2K Escalator gets around this limitation by converting and telling Photoshop that the image is either greyscale or Red-Green-Blue (RGB).

Advanced Settings
If you have permissions and the know-how to edit the registry on your computer, there are a few J2K Escalator settings that you may adjust. If you are unsure what the registry is or how to edit, it's best to skip this section. Modifying your operating system's registry improperly can harm your computer. Future versions of J2K Escalator may offer a more user-friendly way to modify these settings. For now though, they can only be turned on or off by manually editing the registry. Available settings are:

  • Thumbnail Level: Many host applications support the display of thumbnails in their respective File|Open... dialogs. Because many J2K files are very large or very complex, creating thumbnails can also be a very complex process and, more importantly, a very slow one. You can control the speed/quality tradeoff of J2K Escalator's thumbnails via a registry string with the following name: HKEY_CURRENT_USER/Software/Stellar Science/J2K Escalator/ThumbnailLevel. Acceptable values for this string are:
    * 0:Do not display thumbnails
    * 1:Display thumbnails but favor speed over quality.
    * 2:Display thumbnails but favor quality over speed. This may be unbearably slow for very large J2K images.

    Future versions of J2K Escalator may offer more fine-tuned control in this area.
  • No Warning Boxes: The Other Warnings section describes a number of warning boxes that can pop up while loading a J2K image. Create a string value in the registry with the following name to turn these warnings off: HKEY_CURRENT_USER/Software/Stellar Science/J2K Escalator/NoWarningBoxes