FitsPlug V1.0.

A Windows Format plugin for Adobe Photoshop.




Page       Section

1              1.  Installing FITSPLUG.

1              2.  Tips.

2.             3. Supported FITS images.

2.             4. Loading FITS

2.             5. Saving FITS.

2.             6. About FITS headers.

2.             7. Fits Conformance.

3.             8. Note on Starlight Xpress one-shot colour Fits images.

3.             9. Support.

3.             10. Single user Licensing and Ownership.

3.             11. Site Licensing and Ownership

4.             12. Prices

4.             13. Disclaimer

4.             14. Contact Information


1. Installing FITSPLUG.


1. Ensure Photoshop is not running.

2. Unzip the FITSPLUG.8BI file and copy it into Photoshop's Format plugins directory.


                For Photoshop V5.0 and higher



                 (where x.x is the version you have installed)


                For Photoshop V4.0


                  \PHOTOSHOP\PLUGINS\FORMATS\ directory.                           


When you start Photoshop, the plugin will be loaded automatically, and the FIT, FTS and FITS extensions will appear in the supported filetypes list when you select File/  'Open', 'Save' or ‘Save As' menu options.


2. Tips.


If there is any sign of instability in Photoshop, remove the plugin from the installed directory and restart Photoshop.


If the image appears black when loaded, try an auto scale on the image after loading into Photoshop, either before or after conversion to 8-bit. Many astronomical images do not fill the entire dynamic range of the image and so may appear black when initially loaded into Photoshop.


Most of Photoshops functions are 8-bit and so will not work on the 16-bit image. Scaling and levelling is functional and with later versions of Photoshop comes more 16-bit functionality so it pays to experiment with later versions. I was surprised to find that the clone tool and Unsharp Mask works on 16-bit files from Photoshop V5.0.


FitsPlug works with PhotoShop CS which fully supports 16-bit images.         

3. Supported FITS images.




                Data Sizes : 8, 16 and 32-bit

                Data Types : Integer and Floating Point

                Colour Fits: 3-plane RGB format.   


Writing :


                Data Sizes : 8 and 16-bit

                Data Types : Integer

                Colour Fits: RGB 3-plane format of 8 or 16-bit data. 


4. Reading FITS.


Most astronomical image processing applications keep the image data separate to the displayed image. This allows the displayed image to be modified for the screen without affecting the data.


Photoshop does not have this ability and displays the image as per the image data. To modify the images appeareance on-screen means modifying the actual image data. For this reason the plugin does not scale the data on load, but rather reads in and displays the image as-is.


The exception to this is 32-bit images. Because Photoshop does not support 32-bit images, the image data must be converted to 16-bit on load. A straight 32-bit to 16-bit conversion will result in data loss but the plugin attempts to do this intelligently by prescanning the image and determining the range of pixel values. The image is then converted to 16-bit using as much of the images dynamic range as possible to avoid data loss. The result is a slightly longer load time but the best overall result.


8 and 16-bit images are loaded without scaling to ensure there is no data  lost. Without the prescan to determine the data range and the fact that there is much less data to load, makes these images load much faster than 32-bit images.


32-bit RGB images will take the longest to load as all 3-planes are prescanned to find the max and min pixel values for scaling to ensure that all colours are scaled equally. RGB images typically contain 3 monochrome images and therefore will take 3-times longer to load than a mono image of the same size.


All internal conversions are 64-bit to avoid data loss.


5. Saving FITS.


All images are saved using the bit depth of the image within Photoshop.


32-bit Integer and Floating-point files are converted to 16-bit when read into Photoshop and saved as 16-bit integer files from Photoshop.


Therefore simply loading and then saving a 32-bit image will result in a 16-bit image.


If a non-FITS (Jpg, Gif, Tiff, etc) colour image is saved as FITS the result will be a colour FITS file with 3 planes in the order RGB, as per Maxim DL.


6. About FITS headers.


Fits headers are now stored within Photoshop as an image resource, retreived on save and updated.


A FITSPLUG identity line will be added if there is room in the header. A new header block will not be created to add the FitsPlug identity line, there has to be room in an existing block.


If the file being saved as FITS was not a FITS file originally (i.e. TIFF, JPG, etc) then a new FITS header is created with only image geometry information in it.


7. Fits Conformance.


Some applications do not create properly conforming Fits Files in that the image data is not padded to a multiple of 2880 bytes.


The Fits plugin conforms to the Fits specification when it comes to reading and writing FITS files, though the plugin shows some leniency when reading FITS files in that the image data need not be a multiple of 2880 bytes as per the specificaton.


In this case, the plugin will still read the file as long as all of the header and image data is present.


Resaving these files from Photoshop will force them into the proper proper FITS conformance by padding them to a multiple of 2880 bytes.


8. Note on Starlight Xpress one-shot colour Fits images.


I received several requests for SX One-Shot colour FITS support, but on looking into the format discovered it was not possible to support as part of a generic FITS loader.


These files require special decoding to interpret the colour information. These images do not conform to the Fits standard because information about the organisation of the colour data does not exist in the header.  For this reason they cannot be told apart from a standard monochrome Fits image.


When interpreted in conformance with the Fits specification, Starlight Xpress One-Shot colour images appear as standard monochrome FITS images. So they will load into Photoshop as a greyscale image.


9. Support.


Support will be provided for issues relating to the Fits plugin as provided.


Requests for new features though not a support issue, are welcomed and features may be added to future versions of the plugin.


Registered owners will receive free updates of minor version releases and a discount on major version releases.


The final beta V0.12 is no longer supported.


Please send support requests to



10. Single user Licensing and Ownership.


By purchasing the plugin, a single user may install and use it as often as needed as long as the computers that the plugin is installed on, all belong to the purchaser and they are not installed for use by others.



11. Site Licensing and Ownership


All purchases of the plugin are considered Single-user licenses unless specifically agreed otherwise prior to purchase.


 If the plugin is to be used on a publically accessible computer, or on more than one computer for use by more than one person, a site license must be agreed upon with Astroshed prior to purchase.


At present, only Fits plugins received directly from me are considered to be legal copies.


12. Prices


                Single-user license:                            USD $30


                Site Licenses

                2-10 users or installations:                USD $20 each

                11-20 users or installations:              USD $100 + $10 each       

                20+ users or installations:                 USD $200 + $5 each


For example, an order for 11 licenses would cost US$100 + 11 licences @ US$10 each = $210.

Site licences may be renogotiated if a Site license is deemed necessary after initial purchase of a single-user license.


13. Disclaimer


Although all care has been taken to ensure that the plugin will behave itself, Astroshed and I accept no liability for any adverse consequences which may arise from the use or attempted use of the plugin.


14. Contact Information


I am interested in your comments or suggestions so don't hesitate to pass them on to me. Good or Bad, at


Eddie Trimarchi.