SMART Image Operations

The image operations window is invoked by clicking on the "Image operations" button on the Dataset Manager. This allows arithmetic operations on two or more dataset images. Once the relevant operation has been performed the results can be shown in the SMTV File Viewer. To use image operations first highlight the relevant images to perform operation(s) on in the dataset window and then click on "Image Operations". This displays the image operations window :

The user can select one of :

• Combine
• Arithmetics
• Multiple Subtraction
• Multiple Division

Clicking "Execute" on the "Image Operations" window performs the selected operation. Clicking "Cancel" on the "Image Operations" window will cancel any operation and return to the Dataset Manager.

Images resulting from Image Operations usually have the FITS header of the first input image placed in them. One or more FITS keywords "S_IMOPnn" is/are added to the header to indicate which Image Operation(s) have been performed. These are listed at FITS Header Keywords.

Image Operations - Combine

Selecting "Combine" on the "Image Operations" window displays 6 options :

Select the operation to be performed and then click on "Execute". The selected operation will be performed and the "Image Operations" window will disappear. The resultant image will be placed at the end of those listed in the Dataset Manager. It will have a type of "IMCOMB". The resultant image will have a default name dependent on the operation selected, unless the user fills in the text field labeled "Output Name (optional):".
The default image name can then be changed with the "Rename" function of the Dataset Manager.

Image Operations - Arithmetics

Selecting "Arithmetics" on the "Image Operations" window displays an entry window where arithmetic operations can be performed on the images displayed. To perform arithmetic operations on images IDL syntax must be used and the images must be denoted by the "!imX" names listed in the window. Type the required operation IDL syntax into the box labeled "Output=". (EG. To add the first two images listed type into the box : im1 + im2).

To perform the operation click on "Execute". The selected operation will be performed and the "Image Operations" window will disappear. The resultant image will be placed at the end of those listed in the Dataset Manager. It will have a type of "IMCOMB". The resultant image will have a default name of "Arithmetics", unless the user fills in the text field labeled "Output Name (optional):". The default image name can then be changed with the "Rename" function of the Dataset Manager.

Image Operations - Multiple Subtraction

Selecting "Multiple Subtraction" displays the following window:

This allows one image in the list (im1-imn) to be subtracted from each of the others. Enter the relevant image name (EG. im1) in the box labeled "Subtract one list item from others:", then click "Execute". The selected image will be subtracted in turn from each of the other listed image(s) and the "Image Operations" window will disappear. The resultant image(s) will be listed at the end of the Dataset Manager, in the order they appeared in the Image Operations list. Each will have a "Type" of "IMCOMB". Each resultant image will have a default name of "[Object name]_subtracted_n", where n was its number in the Image Operations list. (EG. "M101_subtracted_4".). The default image name can then be changed with the "Rename" function of the Dataset Manager.

Image Operations - Multiple Division

Selecting "Multiple Division" displays the following window:

This allows one image in the list (im1-imn) to be divided into each of the others. Enter the relevant image name (EG. im1) in the box labeled "Divide one list item from others:", then click "Execute". The selected image will be divided in turn into each of the other listed image(s) and the "Image Operations" window will disappear. The resultant image(s) will be listed at the end of the Dataset Manager, in the order they appeared in the Image Operations list. Each will have a "Type" of "IMCOMB". Each resultant image will have a default name of "[Object name]_divided_n", where n was its number in the Image Operations list. (EG. "M101_divided_4".). The default image name can then be changed with the "Rename" function of the Dataset Manager.

Error and BMASK Plane during Image Operations

For a full explanation of how the error and BMASK planes are treated during SMART Image Operations see : Error and BMASK Plane during Image Operations.