Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

ISIS Documentation

makeflat

Create a flat-field image for line-scan instruments

This program creates flat-field images for line scan, push frame, and framing instruments. All input cubes should have the same number of samples; any images in the list that do not have the same number of samples as the first image will not be used. The names of the cube files used to create the flat-field image must be entered using an ASCII file (FROMLIST) with one filename per line (any line beginning with a '#' or '//' is treated as a comment). The specific equation for each camera type is below.

  • Line Scan

    • A frame is a NUMLINES line section of data. The equation for the final single line, single band, flat field file is:
    Sum( Sum(FrameColumn) / Average(Frame) * ValidPixels(FrameColumn) ) / TotalColumnValidPixels

  • Push Frame

    • The equation for the final single framelet, single band flat field file is:
    Average( PixelInFramelet1, PixelInFramelet2, PixelInFramelet3, ... )

  • Framing

    • The equation for the final single framelet, single band flat field file is:
    Average( PixelInCube1, PixelInCube2, PixelInCube3, ... )

Warning: This program creates potentially large temporary files

Categories

History

Tracie Sucharski2007-06-20 Original version, Adapted from Isis2 version of makeflat.
Steven Lambright2008-05-13 Removed references to CubeInfo .
Steven Lambright2008-06-11 Changed algorithm and added support for framing and push frame cameras.
Ian Humphrey2014-06-23 Cleaned up spacing in pushframe test Makefile

Parameters

Files

Use this parameter to select the file which contains a list of cube filenames to be used to create the flat file.
Type filename
File Mode input
Filter *.lis

Output flat field cube
Type cube
File Mode output
Pixel Type real

Output PVL-formatted file of all excluded files and sections of data.
Type filename
File Mode output
Internal Default None

Statistical Options

For a framing camera, this is the maximum standard deviation of each image. For a push frame camera, this is the maximum standard deviation of each framelet. For a line scan camera, this is the maximum standard deviation of NUMLINES lines. Data that exceeds this standard deviation will be ignored.
Type double

Image Options

Line scan cameras collect a cube a single line of data at a time. Push frame cameras collect multiple lines of cube data at once. Framing cameras collect an entire cube of data at once.
Type string
Default LINESCAN
Option List:
Option Brief Description
LINESCANLine scan camera Line scan cameras collect a cube a single line of data at a time. This option makes the flat field a single line of data.

Exclusions

  • FRAMELETHEIGHT

Inclusions

  • NUMLINES
PUSHFRAMEPush frame camera Push frame cameras take multiple lines of cube data at once. This option makes the flat field a single framelet of data.

Exclusions

  • NUMLINES

Inclusions

  • FRAMELETHEIGHT
FRAMINGFraming camera Framing cameras collect an entire cube of data at once. This option makes the flat field the size of one of the input images.

Exclusions

  • NUMLINES
  • FRAMELETHEIGHT

LINESCAN

A single line often does not have enough data in it to perform good tolerance calculations. The tolerance calculations will be performed on this many lines as a time, and if found to be invalid, this many lines will be excluded from the output flat file calculations at a time.
Type integer

PUSHFRAME

Push frame images consist of framelets. The framelet size needs to be known in order to make a flat field file for a push frame camera.
Type integer

Example 1

Line Scan Cubes

This program was run on 65 hirise images to produce a flat file, and one of the images was calibrated with the flat file.

Command Line

This is a typical run for makeflat. files.lis is a list file generated by a "ls *.cub > files.lis" command. The files inside of files.lis are between 20,000 lines and 200,000 lines of data (variable length). The file flat.linescan.cub is the flat-field output given these cubes and the file exclude.txt is a detailed output of what was excluded.
makeflat fromlist=files.lis to=flat.linescan.cub exclude=exclude.txt stdevtol=30 numlines=100

GUI Screenshot

Line-Scan Run

This is a typical run for the linescan mode

Line-Scan Run

Parameter Name: IMAGETYPE

This is a typical run for makeflat. files.lis is a list file generated by a "ls *.cub > files.lis" command. The files inside of files.lis are between 20,000 lines and 200,000 lines of data (variable length). The file flat.linescan.cub is the flat-field output given these cubes and the file exclude.txt is a detailed output of what was excluded.

Line-Scan Input Image

This is a section of one of the inputs listed in files.lis

Line-Scan Input Image

Parameter Name: FROMLIST

This is the input to makeflat. Notice the vertical lines persistent throughout the image and the dark area on the right-hand side.

Line-Scan Calibrated Image

This is input that has been calibrated

Line-Scan Calibrated Image

This is the same section of image data as before, except calibrated with the flat-field file that was generated by dividing by the flat field file. The vertical lines and darkness have completely gone away.