Using Fiji (imageJ2) I was able to open a sample .jp2 file provided at http://www.fnordware.com/j2k/jp2samples.html
-- it opens as a stack of 3 bands which using Color -> Stack to RGB did recover the original image, suggesting it would open as many bands as are present. (It's important to quit Fiji regularly and restart, to pick up all the updates.)
Even this small simple file gave an error message in Gimp and opened recognizably but very bizarrely in Safari, as all-black in Chrome, and not at all in Firefox. Preview in Mac Yosemite can save to JPEG2000 but not open files in that format! The forum will not load .jp2 files. The computer world is awash in file formats that no one is interested in supporting and this is one of them.
The sample file above is probably not signed but note it already shows this file format standard is rarely supported, which you can also see in the obsolete list of supporting software at wikipedia.
The link you provided does not work in Firefox because Sentinel links use parenthesis which are unacceptable in urls (replaced by spaces) but do trigger the download in Safarihttps://scihub.esa.int/dhus/odata/v1/Products('a04ba2a6-352d-4b32-a5a8-367ede20ccbf')/
I wonder what ever possessed them to use this file format which never gained any traction and for most practical purposes had been abandoned before they ever adopted it. Using signed when they didn't use signs suggests again, like granule instead of tile (and elsewhere the peculiar word choice 'manifest' and SAFE which have nothing to do with manifests or safety), they don't know what they are doing.
Or live in their own little world of a specialized proprietary software where they are saving these files out of, maybe thinking they were making an advancement over regular jpeg discrete cosine with wavelets. People can do wavelets (a variant on fourier transform) on their own time, that is supported everywhere (Gimp, ImageJ, ImageMagick).
Granule may mean something larger than a tile though it should really mean something smaller (grain). Or it may be synonymous. In some places, they speak of using GML-JPEG2000 format rather than JPEG2000 (aka .jp2). Amusingly, comments are welcome even though NO COMMENT BOX is provided!
Geography Markup Language (GML) has many pages of 'standards' of its own http://www.opengeospatial.org/standards/gml
The basic (?) idea is:
GML serves as a modeling language for geographic systems as well as an open interchange format for geographic transactions on the Internet. As with most XML based grammars, there are two parts to the grammar – the schema that describes the document and the instance document that contains the actual data. A GML document is described using a GML Schema.
Yes but 'GML Schema' just sends you off on another unending chase for an explanation or example. There is a disconnect between people who sit on formal standards committees and their target audience which, unbeknownst to therm, is larger than fellow programmers. They are seeking the most general possible abstraction and so enable a vast hypothetical feature set, the problem being no one implements a tenth of it in the real world, so all the complexity was for naught.
Landsat has 11 bands, S2A only 13. Why not simply do .tiff like Landsat did? Or why not just use the vastly more efficient lossless .png? I think the whole problem is trying to do too much in overly general schemas. The end users just want a simple graphics file they can open and process in their favorite among the innumerable programs and platforms in use. It just gets more balkanized every year.
Google search on GML-JPEG2000, JPEG2000 and jp2 shows that the #1 interest is in file converters that get you out of GML-JPEG2000, JPEG2000 and jp2 into something recognizable. However I found the free file converters only supported part of the format's core, not the whole schema.
Nothing about 'signed' in their explanation, in fact it seems ruled out by 'radiance value' and 'physical gain factor':
Each pixel value is encoded in 12 bits and is directly proportional to radiance values using physical gain factors. The image data is provided by a set of raster files, either a file per spectral band and per granule, or a file per spectral band and detector [explained somewhere else?] corresponding to the aggregation of granules along track. Each image file is compressed, in LOSSLESS mode, using the JPEG2000 algorithm.
Their server situation is a joke. It takes several minutes to search S2A* even though there is just one such file; then they send the 1.5 GB zipped file over a very slow connection that tends to disconnect repeatedly as well as time out during the download, which I see all the time in Sentinel 1-A too (but not elsewhere such as Landsat). It does no good to have a fast connection facing a slow server -- ironic since their annual budget is a million times mine.
Given the difficulties, what was the purpose of only offering a gigantic sample file? That is only going to compound the issues of users trying to find software that even opens this rarely implemented rarely used 15-year old 'standard'.
I've attached a full size uncompressed version of their incoherent explanation. Any questions? (The 305 character url had to be shortened, http://tinyurl.com/nf8dsnj
I eventually located the help desk last week after much surfing of their site and submitted a polite reasonable question to which they eventually responded with a very helpful explanation about re-projecting Sentinel-1 into Landsat UTM. http://forum.arctic-sea-ice.net/index.php/topic,1355.msg60306.html#msg60306
The whole bewildering, disorganized redundant Sentinel site is a prime example of incompetent technical writing which they seem to have contracted out and then been stuck with (not really caring). It does go through the motions of explaining Sentinel use and evidently that was enough to get a pass on contract terms.
The Sentinel satellites are advanced scientific instruments with sophisticated capabilities. Oh, by the way, they take ground pictures too. Through dark and clouds with high repeat coverage. Sadly, their boorish end users just want these pictures.
Indeed google search suggests that the primary known users globally of Sentinel satellites have been DMI and 4-5 people on these forums.
This happens with a great many satellites. The PIs write a paper or two using all the design capability, maybe a daily online product that attracts little interest and soon becomes obsolete. Some minor aspect of the capability still attracts some users. The terabytes of data continue to pile up but user interest has died. After a while, the ground station's budget moves on and data is no longer collected or served, leaving the poor satellite transmitting away but nobody receiving.
I've noted before with Sentinel 1A that even the massive IW high resolution files barely provide a better picture than a lowish resolution preview DMI. This suggests that they could carve out the pictures from Sentinel
and serve them separately at moderate resolution as .pngs, thus eliminating 99% of the demand on their servers.
In summary, the Sentinel office does exactly as they please, there is no accountability or interaction with the external user community. Ok, but why offer a public server and encourage people to register? All this for the crappy ground resolution (Italy above) that will amount to 99% of end use.