In terms of compression, what is RAW?

I have been reading about the Pocket Cinema camera, but don't understand what happened back in November.

The press release states:

The new Blackmagic Camera 1.5 software update adds CinemaDNG RAW file recording so customers can now capture super wide dynamic range in a single file.

The Blackmagic Pocket Cinema Camera uses the open standard lossless compressed version of CinemaDNG RAW. CinemaDNG RAW lossless compression works in a similar way as a ZIP file where the RAW files are compressed during recording without the loss of any part of the image, so all images retain the same quality when they are decompressed. That means customers get back the mathematically perfect high quality RAW file image that they recorded.

Is this correct -- Before November, the Pocket Cinema camera could do CinemaDNG lossless. It would save one frame at a time.

Now CinemaDNG RAW saves all the images as one file. Is there any additional compression done on the combined images?

According to the CinemaDNG Specification, lossless Huffman JPEG is used to compress individual images. Therefore, I think there is/was Huffman table created for each individual image.

According to the CinemaDNG RAW press release from above, it seems like the software now just "zips" the images into one file.

Any help here is greatly appreciated.

JJ

the Pocket never did uncompressed Raw. It has always been Raw. and It stores them still as induvidual DNG frames. They have a lossless compression applied to them which is very subtle, and truthfully less compressed than some other "raw" flavors out there (though that is almost an oxymornon...)

They are not "zipped," they are stored in a folder per clip from start to end of record and like all cinema raw sequences, they are interpreted as one file (akin to when say a clip was spanned and the programs recognized that) but only when opened in a proper program (resolve) If you looked at them in windows explorer, on on my mac, you'd see a series of .dng files.

However the important point is that it is file compression, not image compression, so when the files are expanded again, there is no loss of image quality.

One can't stress this point enough: "compressed DNG" is still pure RAW, with every bit of information accounted for, as there is only lossless compression applied. So there are no "compression artefacts", or any other form of image degradation. Compared to the uncompressed RAW DNG from the 2k5 CC the Pocket cams compressed Raw even has the advantage of easier handling and significantly smaller storage consumption - that's why the CC 2k5 owners look jealously at the Pocket cam and demand the same compression algorithms to be ported to the 2k5 CC asap.

Even if the BMCC never supports lossless compression, it would be nice to have a utility to convert uncompressed DNG -> compressed DNG.

Can Resolve not do that final workflow? Though it may seem a bit moot. Makes more sense probably to just shoot it over to an offline format and then conform back to camera original. Granted, that sucks for storage space while the project is still hot.

Can Resolve not do that final workflow? Though it may seem a bit moot. Makes more sense probably to just shoot it over to an offline format and then conform back to camera original. Granted, that sucks for storage space while the project is still hot.

via Cineform RAW plugin

Jules

Adobe Digital Negative (DNG) converts to the lossy DNG per current DNG specification, v1.4. The compressed files it creates could not be opened in the versions of Premiere and Resolve 10 I was running a few weeks ago. Not revisited since.

I was able to load the compressed DNG files rendered from the DNG converter as an image sequence in After Effects. I probably could have linked that AE project file back to Premiere or linked for non-real time playback, requiring a pre-render of the Premiere timeline. I can't remember exactly.

BMD may or may not be making their own lossy method for cDNG with the BMPC 4K, we will see in due course. The lossy compression in the Adobe app was orginally created for photographers.

Adobe Digital Negative (DNG) now, version 8.3
http://www.adobe.com/au/products/photos ... yTab2.html

One can't stress this point enough: "compressed DNG" is still pure RAW, with every bit of information accounted for, as there is only lossless compression applied. So there are no "compression artefacts", or any other form of image degradation.

Yes, that is important to note. Hence the reason I called it file compression, not image compression.

That's still incorrect, because you're basically equating "image compression" to lossy compression, which is invalid. Images can be compressed losslessly, which is actually quite common. A lot of digital SLRs support compressed raw capture, for example. TIFF supports lossless compression as well. The compression algorithm that BMD is using for the BMPCC files is one of the Adobe standard ones (it may be the one that BMD developed and submitted to get standardized), which is an image compression algorithm that happens to be lossless.

No, it is not incorrect. Blackmagic themselves say that they use mathematical file compression on the files. To quote from the Blackmagic FAQ section: "Blackmagic Pocket Cinema Camera uses a lossless compression when recording CinemaDNG RAW. This means only the data is compressed and no part of the image is lost. You can think of it like a compressed ZIP or RAW file on your computer. When uncompressed, the file is exactly the same as before compression."

Well, since you think you know everything because you can regurgitate an FAQ entry, then never mind.