Rectifying Jpeg2000. What gives?

[JasonMarcinski]

If I rectify a jpg2000 in Arc it takes 10x longer than a jpeg or tiff to resample. Secondly, the output file size is 2-3 times larger than the input jpeg2000 file that I started unless I set the quality to 10.  This does not happen with jpeg.

Is this normal?

[TimothyHales]

You are probably looking at compression differences between the formats.  JPEG2000 (20:1) uses a higher compression ratio than JPEG (10:1) and TIFF.  Additionally, the output compression quality is probably different from the input.

Raster compression

[JohnSobetzer]

Thales007: In regards to compression quality, what is the setting on the ArcGIS 1:100 scale that produces a 20:1 or 10:1 compression for jp2, or jpeg?  I assumed it was 100 divided by the compression desired (e.g. 100/20 or 5 gives a 20:1 compression) but the jp2 file sizes ArcGIS produces do not match with those of GeoExpress which states compression in terms of 10:1, 20:1 etc.  I assume they use different algorithms and there is some variation in jp2s, but at least in my latest work the GeoExpress setting produced the expected compression and ArcGIS's was noticeably less.  This was using ArcGIS 10 beta 2 in a direct conversion rather than a rectification.

Marcinjz: It does seem that this newer version of ArcGIS produces jp2 much faster than 9.3 (it is able to use multiple cores during this conversion) and the resulting jp2s work better in ArcMap, but I haven't tried to objectively prove it.  I don't know what version of ArcGIS you are using but my 9.3 just didn't seem to do well with that file type.

[JasonMarcinski]

Ok, that would explain the longer processing times, but Im still confused about file sizes.

If JP2 has twice the compression ratio as JPG, then why are the rectified file sizes of my JP2 larger than JPG at the same quality setting? For example if I rectify an image the JPG file size would be ~6MB vs ~40MB for the Jpeg2000 image given the same quality setting for both (10 in this case).

I notice rendering is much faster for the JP2 vs JPG and wouldnt this also be due to compression differences or does this have to do with Tiling


Regarding Arc 10 vs 9 processing, Yes I have noticed an increase in performance except my copy seems to hang or become unresponsive half the time during JPEG2000 resampling and I have to force close

[TimothyHales]

Yes, a compression quality of 5 would give a compression ration of 20:1.  As for comparing the output file size, there may be some differences with the algorithms.  Also verify theoutput pixel size is the same.