Luminous Landscape Forum

Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: torchiam on September 03, 2011, 12:31:15 pm

Title: file size question
Post by: torchiam on September 03, 2011, 12:31:15 pm

hi everyone

i noticed that on the brand official web site，leaf 80 megapixels back has a larger file size than IQ180.and hasselblad also provide a larger file even with less pixels than Iq180,if i remember it right.

could anyone here explain the reason?

thanks

Title: Re: file size question
Post by: John R Smith on September 03, 2011, 12:39:08 pm

The RAW files from MF backs are usually compressed (lossless compression) by proprietary algorithms in firmware. So the size of different manufacturers RAW files will vary, even for the same Kodak chip and number of megapixels. My Hasselblad 3FR files vary according to the complexity of the image, which limits the amount of compression which can be applied.

John

Title: Re: file size question
Post by: torchiam on September 04, 2011, 10:09:35 am

thanks John

i understand that the size of files could be different because every image contains different amount of information.

but IQ180 is the largest sensor in term of single shot ccd.so what you mean is IQ backs has a better lossless compression solution than leaf backs?

Torchiam

Title: Re: file size question
Post by: lance_schad on September 04, 2011, 10:33:52 am

Some info on Phase One IIQ formats:
"IIQ RAW S and IIQ RAW L
Phase One digital back users can choose between storing their tethered captures in two different types of compressed RAW files.

IIQ RAW stands for Intelligent Image Quality RAW. It is an intelligent way of turning the full 16 bit image data captured by the camera into a compact RAW file format.

The IIQ Large RAW format is unique because it is completely lossless. IIQ RAW Large can be processed into a 16 bit TIFF, even though it is only half the size of a traditional RAW file.

The IIQ RAW Small format is based on the full 16 bit data that is captured by the digital back’s CCD. However, unlike IIQ RAW Large, it is not 100% lossless. Most users will not notice any quality difference between the two file formats especially if the IIQ RAW Small format capture is well exposed and set on a low ISO rating"

For example I just checked out some shots I did recently with the IQ180 and the IIQL files were between 72 and 80 MB while the IIQS files were 42 and 48MB.

Lance