Sony A7RM4 Compressed or Uncompressed Raw

[DrJohn]

I'm not sure which to choose, compressed or uncompressed raw. The default is compressed raw.

Any thoughts on the subject?

John

[Vernon]

Uncompressed 14-bit raw file stores 16,384 tonal values of a color.

Compressed uses 12 bits and thus 4,096 possible values.

Depends on your personal preferences - do you want the ultimate quality(and can you actually see it) or are you fine with the high quality 12 bit offers, along with the smaller file size.

[DrJohn]

I just got the camera and need to do some testing. Compressed raw is the default, which translated to a file size of 62 mb. I need to find out what the file size is for uncompressed.

John

[DrJohn]

I tested it today and got:

Uncompressed Raw: 123.4 mb

Compressed Raw: 62.2 mb

Extra Fine Jpeg: 48.5 mb

John

Edited September 16, 2019 by DrJohn

[PHDX]

Hi, I also got the A7RIV one week ago : I do shoot mainly portraits and landscape and for those  use the uncompressed raw to get the very best (I very often print with A2 or A1 formats). For other purposes such as action, events, I shall use the compressed raw which is quite sufficient;

[MaTiHH]

On 9/16/2019 at 5:23 PM, Vernon said:

Uncompressed 14-bit raw file stores 16,384 tonal values of a color.

Compressed uses 12 bits and thus 4,096 possible values

Just for clarity. The fact that the camera could store more different color values doesn‘t mean it actually does so. 

[Chrissie]

4 minutes ago, MaTiHH said:

Just for clarity. The fact that the camera could store more different color values doesn‘t mean it actually does so.

This is an interesting remark, although it did take away some of the clarity I thought I had.

Obviously you need an "image" source in reality, which actually contains enough different color values to saturate the number of recordable colors. Think of a sunset with a continuous  (speaking in analogue terms) gradient of hues from orange to dark blue. Can you "spend" all 16k values on shades of blue alone, or do you have to leave some slots unused for shades of green, which are not contained in the image source?

[erick]

I choose uncompressed and convert them all into dng

[Bernard0368]

Sorry too jump into this, Erick what are you using for a raw converter. I downloaded some sample images as I am looking to purchase this camera. My Adobe DNG 11 and DXO photolabs don't seem to support the files.

Thanks

[Hobie]

@ Chrissie - You are  right in a continuous tone gradient is where you will really see the lack of bit depth.  We used to see this as banding in the early days of digital images (8 bit  256 colors) .  There just wasn't enough colors to accurately provide a smooth color transition as seen in a clear blue sky.  

Yes, each pixel has the ability to carry 16bits of color/density information.  It is not allocated to a specific color.  Splitting hairs though, remember the sensor has dedicated pixels for RGB ( Bayer pattern) but each will have a full 16 or 14 bit available. 

Also, in practice, keep  mind your output device.  Most color wet digital printers are 8 bit devices.  So your huge files will be automatically downsampled by the printer.    Some of the fine art guys using inkjet printers can use 16bit files.   This higher color density will really lay down the ink.  It may not actually be enough difference to see as those dots are very small and dependent on the paper used. 

So as mentioned,  what you use depends on your intent.  For example, a once in a lifetime landscape, shoot uncompressed raw.   For fast zillions of images during a sports match, fast and jpeg probably is fine. 

 

@ Bernard0368 - Sony has a free software called Imaging Edge and Capture One has free Sony version to convert your files to Tiff or whatever. 

Edited October 19, 2019 by Hobie

[Hobie]

One more thing.  The increased bit depth is very helpful when you are trying to pull out shadow detail or preserve highlight detail in a very contrasty scene.   So if you have a fast enough computer and enough drive space, shoot big and you can always crop and downsample later.  Upsampling or interpolation is not satisfactory. 

[Bernard0368]

Thanks Hobie.

[Monochrome]

On 10/18/2019 at 5:37 AM, Bernard0368 said:

Sorry too jump into this, Erick what are you using for a raw converter. I downloaded some sample images as I am looking to purchase this camera. My Adobe DNG 11 and DXO photolabs don't seem to support the files.

Thanks

Note that last I checked, if you want to use the more specialized DXO PhotoLab features such as DXO's Prime noise reduction, you must use the camera's native Raw file format(s). In the case of Sony, either the compressed or uncompressed native Sony file format. If you convert the Sony file to DNG (even non-lossy compressed DNG), you can not use some of DXO's features.

Converting the uncompressed Sony files to non-lossy compressed DNG files is otherwise attractive because on a7r2 files this typically results (depending on the particular photo) in DNG files that average slightly smaller than the same scene saved in Sony's lossy compressed Raw file format.

If you wonder why Sony did not use a similar non-lossy compressed Raw, it is a matter of computer processing power. Producing these smaller non-lossy compressed files would take too long using the camera's processing power. With a reasonably fast desktop computer, it still takes a few seconds per file.

Edited October 26, 2019 by Monochrome

[JPT]

Sony should offer lossless compressed files, I don't mind if it requires more processing time and slow things down, having the option would be nice when you don't need full speed