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PeterCPC

File Formats

Question

I have been recommending BYE on Stargazers Lounge and in the latest thread http://stargazerslounge.com/topic/260471-imaging-jupiter-with-dslr/I pointed out that you can capture AVIs and CRAW images.

 

Others are pointing out that the data is downloaded as a series of JPEGS and saying that it is compressed.

 

Could you confirm this please as I don't know the answer.

 

Peter

 

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Peter,

 

The LiveView data that is provided to BYE by the Canon SDK and the camera is indeed a series of JPEG images which BYE assembles into an AVI.  Because the image is designed to display on the LCD screen, it is reduced in size to fit that screen.  That is the reason for the recommendation that you use the 5X Zoom feature in BYE for Planetary capture.  This results in a full-sized image that is cropped to fit on the LCD screen.  I do not believe that how or if Canon compresses the color palette for the image is published. Just because the files are JPEGS does not mean that they are compressed to reduce the color palette.

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I pointed out that you can capture AVIs and CRAW images.

 

Thanks. So are you saying that the resolution would be equal to uncompressed files? Also, are the RAWs compressed and made up of JPGs?

 

It's hard to know where you were advised that BYE produces "CRAW" files, as in the Forum Thread that you posted it was You that posted that tidbit.

I assume that you imply "Compressed RAW" file data.

 

BYE downloads the RAW Files which the Canon DSLR produces, nothing more.  The Camera's Onboard DIGIC Processor reads the Sensor Data and packages it rather "Unprocessed" (hence "Raw") into the CR2 File.

Depending on the model of DSLR, most Canon EOS Cameras offer a Choice of RAW File Sizes (Full, Medium, Small).  Of these, only the "Full"-sized RAW should be of interest because the CAMERA (not BYE) performs In-Camera Resizing (Interpolation) to reduce the Resolution and hence the File Size for the "Medium" and "Small" Files.  Canon EOS DSLRs also offer choices on the Size of "Accompanying JPEG File" which the Camera can produce along with or instead of the RAW File, and BYE will also Download that file.

 

Canon RAW "CR2" File Formats do have some Internal Compression - but it has been shown time and again to be Lossless Compression.

 

There are other Brands of DSLRs which have Lossy Compression in their RAW Files - some Sony Models were plagued by this practice.  But even then, that was a choice of the Camera Manufacturer not an Image Capture App Developer.

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As Rick said BYE does not alter any images coming out of the camera, be it live view images or raw image files.

 

Whatever your camera provides without any software (live view stream and still CR2/JPG images) is what BYE provides your with software.  BYE does not introduce any kind of compression in the AVI creation... it is as-is coming out of the camera, then added to a single avi file with NO additional compression.

 

Hope this helps,

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