Tells img2png to create thumbnail files in addition to full size files. N is an optional integer value that can be used to specify the thumbnail size. If N is not specified a value of 4 is used. The thumbnail images are automatically contrast stretched. Example:

img2png *.img -t8 (or img2png *.img -thumbn8)

This will create thumbnail files in addition to the full size files. In this example the thumbnails are 1/8 the size of the full size images.

This tells img2png to perform radiometric correction (the default is not to do so). You will want to do this when working with RAD files from the Mars Exploration Rovers (MER) and also when converting Cassini images.

Here NNNN is a floating point number (e.g. -s12). The image is multiplied (scaled) by NNNN after it is converted (or radiometrically corrected if -r is used). This is sometimes necessary since the images are often very dark without this. The default value if -s is not used is 8 for MER (when radiometric correction is used) and 1 for everything else. These values should work well in most cases. Note that the PNGs will often look very dark without the -s option, especially for MER images. The reason is that 16 bits yield an intensity range of 0-65535 but in most cases I have seen the maximum intensity is much lower than 65535. The main exception is RAD MER files.

This tells img2png to write the image labels to separate text files. The text files typically are named image.img.txt where "image.img" is the name of the original input file. Only a subset of the labels (some of the more "interesting" ones) are written to the text file.

Tells img2png not to create any PNG files. This can be used to check for bad input files or for creating thumbnails only.

Specifies the name of a file (Contrast stretch Table) containing contrast stretch parameters (e.g. -ctcontrast_stretch.txt). This applies only when converting FITS files. The contrast stretch file looks like this:

0 3800
0 25
0 32

This means that for image 1 in every FITS file, pixels with intensity <=0 will be set to black in the output file and pixels with intensity >=3800 will be set to white. The 0 and 25 parameters apply to image 2 in each FITS file and 0 and 32 to image 3. Any of the numbers in the file can be replaced with a "-" (without quotes), meaning use the minimum intensity value in the image (if "-" is specified instead of a minimum value) to determine the contrast stretch. Replacing the maximum value with a "-" has a comparable effect. To determine applicable values for the contrast stretch parameters, first run IMG2PNG with the -n option. IMG2PNG will output the minimum and maximum intensity found for each image number.

The black horizontal stripes that are sometimes present in Cassini and Voyager images can be removed using the command line option -destripe. They are removed using linear interpolation. Linear interpolation is not optimal; in a future version a better (and more complex) algorithm will probably be used.

Images with non-square pixels can be resampled to square pixels using the -resample command line option. At present the NEAR MSI images are the only images that get resampled (this is because at present these are the only images I know of with non-square pixels).

The filter name(s) can be included in the output filename using the -fnamefilter command line option and the observation id using the -fnameobs command line options.

Adds _hflip and/or _vflip to the output filename if IMG2PNG has flipped the image horizontally and/or vertically. See also (13).

Calibration files can be specified using the command line option -calib. This is implemented as suggested in machi's post at Unmanned Spaceflight: http://www.unmannedspaceflight.com/index.p...st&p=170463
So if you have a file named flat.txt (as in machi's example) use "-calibflat.txt". If this option is used the bias and darkframe are subtracted from the image and the result then divided by the flatfield. Individual calibration files are optional so you can for example omit bias correction by omitting the "b=" line (or commenting it out by prefixing the line with ; or #). If the input image is 8 bits it is converted to 16 bits before calibrating.

Here F1 and F2 are floating point numbers, for example "-fstretch0,0.1". This parameter is applicable when converting images containing floating point data and is used to specify how to map the floating point data to 2 byte integers in cases where IMG2PNG doesn't 'know' which parameters are applicable. If this is not used, IMG2PNG uses the actual range of the data when it isn't 'familiar' with the data and otherwise it uses built-in parameters that differ for different missions/targets.

-fstretch is also useful for forcing IMG2PNG to use the same parameters for many images which is necessary when doing color composites. To get a rough idea of which fstretch values might be good first run IMG2PNG without -fstretch and notice a line in the output that looks like this:

Floating point to 16 bit integer conversion: [-0.000023,0.059897] -> [0,65535]

This suggests that -fstretch0,0.06 might be good - or maybe -fstretch0,0.1 to avoid getting saturated areas for images where different and 'brighter' filters might have been used.

By default IMG2PNG flips images horizontally and/or vertically when necessary to get a correctly oriented output image. -noflip can be used to prevent this and get an output image with the same orientation as in the input file. Exception: IMG2PNG will always flip LRO images when needed, even if you use -noflip.

Removes reseau marks if applicable. These are dark regularly spaced dots that appear in older images taken using 'pre-CCD' cameras. IMG2PNG can remove reseau marks from Voyager, Viking, Mariner 9 and Mariner 10 images.

Controls the amount of information written to the screen when converting images. NNN is a number from 0 to 100. Typical values to use are 0, 1, 10 and 100. The default value is 0.

Fixed a bug which caused the resulting images to be incorrectly oriented (mirror-flipped up-down) in all cases if the input files were in FITS format. Changed the -t command line switch to make it possible for the user to specify the thumbnail size. Various minor bug fixes, the biggest of which involved the conversion of Clementine images.

Fixed a few fairly minor bugs and added several Dawn-related improvements. Added the ability to remove reseau marks from Voyager, Viking and Mariner 9 & 10 images (the -remres command line switch).

By default IMG2PNG now always flips the images horizontally and/or vertically if this is necessary to get a correctly oriented image and if IMG2PNG knows that this is necessary. This affects the conversion of Dawn and Rosetta images. This behavior can be disabled using the -noflip switch. -fnameflip can be used to add information on if/how it flips the image to the output filename.

Fixed a few bugs, most of which affected the conversion of input files containing floating point data. In particular, this new version has better support for the Messenger orbital data, Rosetta data and the LROC and HiRise DTMs. Also added the -fstretch command line option.

A complete rewrite of most of img2png. It is now easier to maintain and it also correctly handles a far larger number of PDS file 'variants' than earlier versions did. Several new features (command line options) have also been added (-destripe, -resample, -fnamefilter, -fnameobs, -calib, -loglevel) and some bugs/problems are now gone. In particular, LRO NAC images can now be flipped so the problem described when the previous version was released  is gone.

IMG2PNG now correctly converts the LRO images (LROC NAC and WAC). The WAC images look weird but this is normal because each image consists of a series of framelets. A future version will correctly account for this. Please note that converting LOLA files has not been tested yet and may not work correctly. Warning: The LRO narrow angle images come in pairs (RC and LC). One of the images from each pair must be mirror-flipped but neither the file headers nor the index.tab files contain enough information to make it possible to determine which image, RC or LC, must be mirror-flipped. Therefore you must manually determine which images to mirror-flip and mirror-flip them yourself. Future versions of the LRO data may contain more information, thus making it possible to do this automatically. SPICE kernels containing the information necessary to do this automatically will also be released in the future.

IMG2PNG now correctly converts the MGS MOLA files. Please note that for the conversion to work you need to download the label files (.LBL) in addition to the image files.

IMG2PNG now generates correct 16 bit PNG files if the source data is 32 bit floating point data that contains information on the valid minimum and maximum data values in an embedded label or a detached label. This means that the MRO HIRISE DEMs now get correctly converted, plus probably a lot of other 32 bit IMG files.

(1) Corrected a bug in the Cassini calibration code. The most obvious and commonly visible effect of this bug was that when doing RGB composites the blue images were too dark relative to the red and green images. This has now been fixed.

(2) Made minor changes based on CISSCAL on V2 of the Cassini calibration volume that became available earlier this year. If you are still using the old version of the Cassini calibration volume I strongly recommend "upgrading" to this new version. It can be found at http://pdsimg.jpl.nasa.gov/data/cassini/cassini_orbiter/ (the coiss_011_v2 files).

IMG2PNG should now properly convert calibrated Messenger images.

IMG2PNG can now convert FITS files to 16 bit PNG files. As each FITS file can contain multiple images and each image may consist of multiple planes the output filenames are of the form NAME_NN_planePP.PNG where NAME is the name of the input file (without the .FITS/.FIT extension), NN is the number of the image and PP is the plane number. If there is only one plane _planePP is omitted and if there is only one image in the input file _NN is omitted. An automatic contrast stretch is applied before writing data to the PNG file; the minimum intensity value becomes black and the maximum becomes white. The contrast stretch can be modified with the -ct command line option. Information on the conversion is written to a log file (img2png_fits.log).

Fixed lots of errors in the Cassini calibration code and made some modifications:

(1) Some files weren't getting closed after use. Because of this IMG2PNG eventually stopped working when calibrating/converting many files in one conversion run.
(2) In some cases IMG2PNG didn't find the flatfielding file even though it existed.
(3) In some cases IMG2PNG didn't find the effective wavelength 'database' file. This was caused by an error in CISSCAL on which the IMG2PNG Cassini calibration code is largely based.
(4) When calibrating Cassini images, instead of displaying message boxes, most of IMG2PNG's errors/warnings are now written to a log file (img2png.log). If this file exists IMG2PNG appends it instead of recreating it. The most important stuff in the file is preceded by "Error:" so you can search the file for anything important. Really severe errors (out of memory, seriously corrupt input files etc.) still appear as message boxes.

Fixed a bug which caused incorrect results when converting the 16 bit calibrated/geometrically corrected Voyager images, especially in dark areas, e.g. the background space. Changed the interpretation of the -s command line option so it can now be used regardless of whether you are using IMG2PNG to calibrate the input images when converting them or not. Previously this value was only used when calibrating. This is especially useful for 16 bit input images with an intensity range of 0-4095.

Made several minor improvements to the code for reading PDS files. Also added two new command line switches:

(1) -l tells IMG2PNG to write the image labels to separate text files. The text files typically are named image.img.txt where "image.img" is the name of the original input file. Only a subset of the labels (some of the more "interesting" ones) are written to the text file.

(2) -n tells IMG2PNG not to create any PNG files. This can be used to check for bad input files or for creating thumbnails only.

Fixed a bug which sometimes caused a crash when calibrating 256x256 pixel Cassini images. Also fixed a bug which caused a crash in rare cases when reading VICAR files. 512x512 and 256x256 pixel Cassini images now get multiplied by 0.25 and 0.0625, respectively when calibrating. This is to make their brightness identical to the brightness of 1024x1024 pixel images.

16 bit Cassini images now get calibrated. Before this only 8 bit Cassini images got calibrated.

IMG2PNG now always complains when a Cassini calibration file is missing. Before this it sometimes simply continued without complaining and skipped the relevant calibration step.

For calibration to work it is not sufficient to download only the IMG files. You must also download the associated LBL files since they contain information necessary for determining exactly how to perform the calibration for the corresponding image.

Finally, note that even if you do not download the CALIB directory you can perform 'partial calibration' since some of the calibration steps do not require data from this directory.