Hello, Dale Kelly wrote: > The 1080P image appears to contain significant "interlace" type artifacts. This may well be an artefact from conversion from .bmp to .jpeg . The original picture was a .jpeg, with properties that I can not seem to extract. I've then cropped it to 1920x1080 and saved it as .jpeg again (with a mild compression factor, as we all have broadband internet). Conversion to .jpeg always gives considerable loss, even when it is "lossless", because the YCbCr components make less efficient use of the 3x 8-bits code space than the original RGB components did. So we can expect quantisation errors from RGB->YCbCr->RGB conversions. But that does not explain what we are seeing here. I know that I have selected sub-sampling ("4:2:0" in video terms) of the CbCr chroma components this time. This is certainly suspicious. For the resolution-reduced images this will be less critical. The visibility of the artefacts from chroma down- and up-sampling depends on the respective algorithms for down- and up-sampling. It may be that different image viewers use slightly different algorithms for up-conversion back to 4:4:4, so that we are not all seeing the same artefacts ! I know that our pfspd viewers deliberately use pixel repetition "to see what's in the file", where a filter would be advised. If you say "interlace" type artifacts, it could also be that you are referring to sampling artefacts in general. Those slanted white lines have been made by somebody applying a rotation algorithm to an originally rectangular image. This requires a sample-rate conversion operation, and we don't know which kind of filter he/she has used. It may have been the standard bicubic interpolator, which may give some more sampling artefacts than my own choice of polyphase filter. These artefacts will disappear by subsequent down-sampling with a better filter, which then dominates because of its lower bandwidth. Remember that pure progressive images can have as many sampling artefacts as interlaced images. (Interlacing is over-sampling, I say.) Regards, -- Jeroen +-------------------------------+------------------------------------------+ | From: Jeroen H. Stessen | E-mail: Jeroen.Stessen@xxxxxxxxxxx | | Building: SFJ-5.22 Eindhoven | Deptmt.: Philips Applied Technologies | | Phone: ++31.40.2732739 | Visiting & mail address: Glaslaan 2 | | Mobile: ++31.6.44680021 | NL 5616 LW Eindhoven, the Netherlands | | Pager: ++31.6.65133818 | Website: http://www.apptech.philips.com/ | +-------------------------------+------------------------------------------+ ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.