A Windows Explorer extension Suite for viewing FITS files .


Online User Guide


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1. What is Fits4Win ?

2.  Installing Fits4Win. 

3 . Installation support downloads.

4. Setting up Explorer for Thumbnail view

5.Setting up a Custom Windows 2000 Template under XP

6. Using Fits4Win

7. TroubleShooting

8. Supported FITS images.

9.  The Fits4Win FAQ

10.  Future Enhancements.

11. Support.

12. Disclaimer

13. Contact Information




1. What is Fits4Win ?


Fits4Win is a combination of programs for viewing Fits files from Windows Explorer. 


Fits4Win was designed as an extension for Windows Explorer so Fits files could be viewed and managed at the file level. There seemed no easy way to visually inspect and manually deal with folders full of Fits images. Fits4Win comprises two main modules; Fits_Thumbs provides Windows Explorer Fits thumbnail support and the Fits4Win viewer provides integrated viewing with some manipulation.  Although file selection is manual, the viewer is designed  to display images with little or no manual manipulation required and incorporates a finely tuned linear stretch designed to work quickly and display low signal, raw images as well as fully processed Fits images.


Summary of features.


- Provides thumbnail view of *.fit, *.fts and *.fits images within Windows Explorer via Fits_Thumbs.

- An optional simultaneous view of the Explorer-selected Fits image in the Fits4Win Viewer.

- Auto stretch parameters are calculated on load

- Images can be loaded raw or with manual or automatically-determined stretch points.

- Individual pixel values can be displayed by left-clicking anywhere on the image.

- Pixel values can be displayed in Hexadecimal or Decimal as selected from the right-click menu. Default is Decimal.

- Image zoom factors can be set to Fit the window size always, or any preset factor from 5% to 500%.

- Optional Fits Header display. 

- Fits4Win is designed to take up as small a screen footprint as possible while still allowing access to other applications, including Explorer.  

- Using Explorer as the file interface allows full windows file handling capabilities on the images being inspected. 

- Fits associations with existing applications are retained, allowing images to be launched into standard image processing applications for further processing or closer inspection.


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2.      Installing Fits4Win.


The following is not as intimidating as it may at first seem. 


Fits4Win requires v1.1 of the Microsoft .net  framework for all operating Systems and V2 of the Microsoft Installer for Windows 2000 and Windows 98. If your system does not have either of these, the Fits4Win installer should recognise the fact and allow you to download and install the required components. If you do not wish to do this during the install, the required components can be installed anytime later. Please see section  3. Installation Support Downloads for details. 


To Install Fits4Win


 - Download and unzip from the Fits4Win page


Run the resulting Setup.exe. Depending on your system configuration one of the following will happen.


For Windows 98 and Windows 2000 installations - Windows 98 installations require the Microsoft runtime redistributable package for V1.1 of the .net framework. If this is not installed, then the installer will detect this and allow the option for you to download and install it. This is a 23Mb download, but once installed will not be required again for any future .net software installations. Links to downloading the latest versions of the Microsoft .net and Installer are in Section 3. Installation Support Downloads.


Once the Fits4Win installer has completed successfully, the Fits4Win Viewer will be installed with an Icon on the Desktop as well as in the Start/ Programs menu. the Thumbnail viewer will have been automatically installed as well.


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3. Installation Support Downloads


Note: It is best to run the Fits4Win installer first to determine if you actually need these.


Because more .net applications are being developed these days, there is a good chance that you will not require any extra support files to be installed as they may be installed already.


The Fits4Win installer should detect and allow instant download and install of any missing components, but if you would prefer to download them independently of the Fits4Win installer, here are the files you may need. 


.NET Framework V1.1
Microsoft Installer V2.0 for Win 98
Microsoft Installer V2.0 for Win 2000


Note: Windows XP already contains Windows Installer 2.0 and so this will not need to be installed if you are using XP. 


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4. Setting up Explorer for Thumbnail view 


Fits_Thumbs is automatically installed as part of the Fits4Win package and is an integral component. All images viewed in the Fits4Win viewer come from Explorer via the Fits_Thumbs thumbnail generator.


For Windows 98 - requires Thumbnail view to be turned on for the folder in question. Two things need to be done. 


    - Enable Web View in Explorer by right-clicking in the folder and selecting "View as Web Page"

    - Right-click the folder, select Properties and check the  'Enable Thumbnail View' checkbox.


For Windows XP


For thumbnails to work in Windows XP Explorer, "Show Common tasks in folders" must be turned on under the Tools/Folder Options menu as shown below.


Note: Windows XP performs undocumented smoothing of Thumbnail previews which modifies the left panel thumbnail view (but not the actual thumbnails themselves).


Fits4Win includes a Windows 2000 template which can be installed under XP that corrects this problem and creates a view exactly the same as the Windows 2000 views shown in this document. See the Win XP Section 2. Using Fits Thumbs below for details of how to set up the Windows 2000 view template for XP.


For Windows 2000 


For thumbnails to work in Windows 2000 Explorer, html must be turned on under the Tools/Folder Options menu .



In Windows 2000 under Tools/Folder Options -  Web View must be enabled as shown above. Active Desktop is not required.

Windows XP does not require this.

Using Fits Thumbs


Note that the Fits4Win viewer does not need to be running for Fits thumbnails to work from Explorer.


With the plugin installed and Windows Explorer setup as described above, the view will depend on your operating system and the view you have selected within Explorer.


Windows 98 will only show you a thumbnail in the left  panel when you click on a filename and doesn't have a full folder thumbnail view.


Windows 2000 provides the best view with each file as a thumbnail as well as a customisable-sized thumbnail in the left pane, when in Thumbnail view.


Selecting a View -Windows 2000 example



The View menu


Note that the view you have selected will apply to only this folder unless you apply the current folder view to all folders under the Tools/ Folder Options/View menu in Explorer. 


From within Explorer in the right-hand side pane, right-click select View from the pop-up menu, you will see which View you are currently using as seen above.  Selecting Details, will show you Explorer like this.


 Details View - All operating systems support this view. It's the best view for use with the Fits4Win viewer.

Select an image by clicking once on the filename. In all views except thumbnail view, you will get a single thumbnail in the left panel, of whichever images you have selected as shown above. If the Fits4Win viewer is active, the image will also load into it.



Thumbnail View  - Windows 2000 allows this view and Windows XP but without the larger thumbnail on the left. However in this view XP will not allow the Fits4Win viewer to work unless the Custom


In thumbnail view, all images in the directory will be displayed as thumbnails, except for Windows 98. It may take a while to generate all of the thumbnails if you have a lot of large images in the directory. If generating a folder full of thumbnails with the Fits4Win viewer active, each image will display in turn in the viewer.


If you want to stop the thumbnail conversion, right-click and select a different view from the View menu. This can be done during thumbnail conversion.


If some thumbnails appears black when loaded, it is probably because that particular image contains low intensities. Fits_Thumbs  uses the same stretch parameters as the Fits4Win viewer. Read the Using Fits4Win section for details.


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Windows XP (as mentioned above) unfortunately attempts some  undocumented smoothing of the thumbnail detail view in the left panel and contain several views which bypass the previewer rendering Fits4Win unuseable. However, the Fits4Win installation includes some tools for installing the much friendlier Windows 2000 Explorer view template. If you wish to try this out, here are the instructions.


5. Installing the Windows 2000 custom view template under XP.


Windows XP's assumptions about images can be quite annoying when you want a true view of images. Luckily though not without difficulty, XP Explorer can be customised to give a true view of images, as Windows 2000 and 98 do. Fits4Win includes some tools to simplify the process and allow XP users the same view as Windows 2000. Here's how


- Install Fits4Win if you haven't already.

- Open Windows Explorer and navigate to the directory you wish to view.

- Right Click on one of the Fits files in the directory and you will notice a new entry "Apply W2k Fits View To Folders" in the drop-down list as shown below.



- Select the option "Apply W2k Fits View To Folders" from the list. 

- From the Explorer menu select "View/Customize this folder" select "Use Existing Customization template" as shown below




- Select OK. 

- Finally as mentioned previously, 'Show Common Tasks in Folders' must be selected from the Explorer menu 'Tools/Folder Options' as shown below.



- On re-entering this folder, you should now see the Windows 2000 view.


- This process must be repeated for each folder which you wish to customise the view of. But personally, I think it is worth it to have a good common view of Fits folders which have not been tampered with by XP.


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6. Using Fits4Win


Note: The Fit4Win viewer application can only be used from Explorer. It is not possible to load an image from the Fits4Win viewer itself


Starting Fits4Win


Start the Fits4Win viewer by double clicking the desktop icon or selecting Fits4Win from the Start/Programs menu. Fits4Win will open with no image loaded as shown below.



If Explorer isn't running, you must start it. One way is by right-clicking the Start button and selecting Explore


The Menu Bar

The Top menu bar functions as follows




Autoscale - Performs an Auto-stretch on the current image.


Auto/Lock/Raw Toggle- This is a three-way toggle switch specifying which stretch parameters will be used for each loaded image.


AutoLoad - An Auto-stretch is performed on each image. This is a tailored linear-stretch to show detail without being too slow.

LockLoad - The currently displayed stretch values are used to scale each image.

RawLoad - Loaded images are displayed using the maximum Range in the image. 


Current Blackpoint. - The current minimum pixel value being displayed. 

Lower the Blacklevel. - Stretch the image keeping the current Whitepoint. Darkens the background. Limited to the minimum pixel value in the image.

Raise the Blacklevel. - Compress the image keeping the current Whitepoint. Brightens the background. Limited to the current Whitepoint.


Current Whitepoint. - The current maximum pixel value being displayed. 

Lower the Whitelevel. - Compress the image keeping the current Blackpoint. Limited to the current Blackpoint.

Raise the Whitelevel. - Stretch the image keeping  the current Blackpoint. Limited to the maximum pixel value in the image.


Full Range . Returns the image to the full range of data in the image. Note: Not the full range for the data type. 

Header On/Off Toggle- Turn Header view On or Off. 


Viewing Images


Open windows explorer if it is not already. This can be done by a Left-Click on the Start button and selecting Explore .


The Fits4Win Viewer will remain On-Top of Explorer (and all other applications) unless this is switched off by de-selecting "Always On Top" from the window menu in the Top-Left corner of the window frame.


Viewing Images is a simple as clicking once on the filename from Explorer. The image will have the thumbnail generated and displayed in Explorer, as well as loading into the Fits4Win viewer. When an image is first loaded, it's size is scaled to fit within the Viewer window.



The thumbnail has no brightness adjustment applied and so without scaling many Fits images would display as completely black as in this example. The image is displayed in the Fits4Win Viewer at 100% Size and has been auto-brightness-scaled. Fits_Thumbs and Fits4Win's Auto-scale apply the same brightness scaling algorithm.


Viewing Headers


Pressing the Header On Button will display the header as below.



The Header window can be scrolled or resized to suit, 

but will always remain attached to either the top or bottom of the image window, 

depending on which has the most room.  


If the Image window is moved the Header window will follow it. And if the Image window is made full-sized, the Header window is switched Off, but can be made visible again by clicking the "Header On" button. The header window will then overlay in it's last position over the top of the image.


Zooming the Image


The image size can be changed by right-clicking anywhere over the image and selecting a zoom factor from the drop-down menu



Right-clicking anywhere on the image will give a drop-down menu, the top option allows the 

Pixel value display to be selected as either decimal or hexadecimal values. 


Inspecting Pixel Values


Pixel values can be inspected by left-clicking on the image as seen in the above image. The mouse cursor can be moved around the image with the left-button down and the pixel values will be displayed according to the mouses current location on the image.



Left-clicking will show the current pixel value as X, Y - L:PixelValue. L is used for as the Luminance value for greyscale images. RGB images show R,G,B values. The displayed pixel value shows the unscaled raw pixel value at that location.


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7. TroubleShooting


Fits4Win viewer does not display the current image


Windows XP - Windows XP attempts to be the most efficient at dealing with folders full of images but actually does us a disservice by this. 


Under Windows XP's Explorer in Thumbnail View, thumbnails will be cached always. Thumbnail cache can be turned off in folder options, but this only means that the thumbnails will be regenerated when the folder is entered. The thumbnail need to be generated to enable the Fits4Win viewer so this means the current image will not be sent to the viewer. The only solution is to not use Thumbnail view (or Filmstrip for that matter), if you want to use the Fits4Win viewer. XP is the only OS suffering from this behaviour. This behaviour can be completely circumvented by installing the Windows 2000 template provided with Fits4Win and explained above in Section 5. Setting up a Custom Windows 2000 Template under XP


The larger side-panel thumbnail is unrecognisable


Windows XP - In all views except Filmstrip and Thumbnail view, a larger thumbnail is displayed to the left of the file-list. Unfortunately Windows XP appears to only display thumbnails as 2-color black and white and so the image is not recognisable. The Fits4Win viewer will however display the image correctly. XP is the only OS suffering from this behaviour. This behaviour can be completely circumvented by installing the Windows 2000 template provided with Fits4Win and explained above in Section 5. Setting up a Custom Windows 2000 Template under XP


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8. Supported FITS images.




    Data Sizes : 8, 16 and 32-bit

    Data Types : Integer and Floating Point

    Colour Fits: 3-plane RGB format.


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9. The Fits4Win FAQ


Q: What is F4W ?

A: F4W is a set of Fits-centric programs designed to allow easier handling of Fits files within Windows. F4W consists of two main programs. Fits_Thumbs is a Windows explorer extension that generates thumbnails in Explorer and passes the selected file information to the Fits4Win Viewer so that the image details can be inspected more closely.


Q: Is Fits4Win an image processing application?

A: No. F4W is a Fits viewer and inspection tool. It's deliberately designed to not attempt to duplicate the processes of bonafide image processing applications and to allow easy access to these applications from Explorer at any time during the inspection.


Q: Why do I need the .net runtime?

A: Microsoft's latest and greatest development platform is called .net and it involves some required additions to older windows systems in order to use the new .net functionality. These additions are bundled as a .net runtime in an installable exectuable called dotnetfx.exe. DotnetFx only needs to be installed once to enable full support for all applications developed using the new .net platform. Eventually all windows will have .net support built-in, the only reason it is required as an addon now is because it is new bleeding-edge technology.


Q: What's this about an Installer v2.0?

A: Microsoft introduced their installer technology after Windows 98. Before this there was no specific installer platform for the operating system. This new generation of installers uses technology that integrates with the operating system in order to promote a more-standardised and flexible approach to installing software. The F4W installation uses some Installer V2.0 functionality and therefore requires Installer 2.0 to install, which is included by default in Windows XP. Other versions of the operating system may require an  Installer update, or in some circumstances, such as a Windows 98 machine with no installer installed at all, will require a download and installation of the version 2.0 Installer. If you ask me that's twice as many installers as should be mentioned in one sentence.


Q: Do I need to associate Fits Files with F4W?

A: No. F4W is not like a normal application in this respect and does not respond to File/Open commands in a standard way. F4W works in conjunction with the fits_thumbs module which is a Windows Explorer extension that generates thumbnails for explorer. So all actions are triggered by selection of a file from within Explorer rather than due to association. This is by design so that existing Image Processing applications can retain their association with the Fits extension and are therefore launchable from Explorer during inspection with Fits4Win.


Q: What happens if I do associate Fits extensions with F4W?

A: F4W will not respond to associations apart from being launched as part of the attempted file load. An image will not be displayed however.  


Q: Why does F4W work in such an unorthodox way?

A: This behaviour is by design. F4W is a Previewer/Inspection viewing tool, not an image processing application. The idea is that you can quickly and easily inspect your images with the full power of the Windows Explorer File handling functions behind you. In Explorer you would use a single click to inspect images in F4W and a double-click to load them into your associated IP application. 


Q: What can I do with F4W?

A: You can load, view, brightness stretch and zoom Fits images from 5 to 500% scales. Some other useful functions are the Fits Header view and individual Pixel Value inspection in decimal or hexadecimal. There are several internal attempts to select optimal auto-stretch parameters so even images with low signal-to-noise ratios will display as much object information as possible to allow a decent visual inspection without manual intervention.


Q: Can I save image from F4W?

A: No. F4W is a viewer and is not intended to duplicate functionality available in Image Processing programs. All available processing is simply to enable an acceptable presentation of the image for viewing the image, object and data. As a consequence, F4W makes a very good fast image viewer alone.


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10. Future Enhancements


Many enhancements are in the works, including:


- More histogram scaling options.. 

- Overlayed Pixel grid for easy identification of pixel boundaries when zoomed in.

- 2x2 and 3x3 Binned Loading

- Bulk Image/directory blinking/animation

- Support for other frequently-used image file formats, like Tiffs and JPGs

- Suggestions?


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11. Support.


Id like to know about any problems/experiences with Fits4Win and can be contacted here


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12. Disclaimer


Fits4Win is currently a beta release and so may not be entirely stable. It has been installed and tested under all of the supported operating systems.


Although all care has been taken to ensure that these programs will behave themselves, AstroShed and I accept no liability for any adverse consequences which may arise from the use or attempted use of Fits4Win.


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13. 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.



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