LtE in CMO #270

From John H ROGERS

. . . . . . . Subject: Re: 'HELP' -- format of images


Dear Clay & colleagues,


Yes, standardisation of image formats would be good. Here are my suggestions:

Naming of files:----------------


Please use file-names representing the date in the order year-month-day. Since the year 2000, I also think it is much better to write the year in full, and to use a 3-letter abbreviation for the month, not a number. Thus: 2003Mar03, not 030303! (It is very confusing to have dates such as 010203, 030201, etc.etc.) I also like to have the observer's initials at the end of the filename.

However we also want filenames that can be compatible with the JUPOS system, to make minimum work for Hans-Joerg and others doing the measurements. The guidelines are on: or


"You can help to simplify measurements if you name each file in the form MDDHHMMM.<extension> where: M ... month (1= Jan., ..., 9= Sep., O= Oct., N= Nov., D= Dec.), DD ... day, HH ... hour, MMM ... minute plus tenth of minute (or just the full minute)." Hans- Joerg, what is your preference for filenames at present?

Data on image: ---------------


Pleae write all essential data on the image - it is much more work to keep track of extra text files. As the JUPOS guidelines say: "Please write date and time(s) of exposure(s), and the colour channel(s) directly to each image, close to Jupiter's disc. Do only use Universal Time (UT) to avoid worldwide confusion. "Also include your name! If you use different cameras or telescopes, or observe from different countries during the year, it is informative to have this information on the image also.

Orientation: -------------


For BAA reports we use south up, because this is compatible with (i) the view seen by most visual observers, & (ii) cylindrical projection maps in which longitude and time increase from left to right, consistent with the telescopic view and the left-to-right flow of western scripts. Some observers are keen to use north up to agree with the preferences of space scientists. It does not really matter, for me or for JUPOS. However I do recommend that you make the belts horizontal, because images have to be horizontal if used for montages or maps, and unnecessary rotations may degrade resolution.

File size: ---------


Of course image files should not be too large. But please use enough pixels to preserve the full resolution of the original image, and do not compress the JPEG file too much - 'high' but not 'maximum' quality is usually satisfactory.

(2 March 2003 email)

John ROGERS (Cambridge, UK)

Jupiter Section Director, BAA

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