Attention: This message is written in "Sony like mode" but remains valid for any digicam manufacturer!

I'm going to translate a post sent from me to the italian newsgroup it.arti.fotografia.digitale.

I've noted that Sony DSC-S70 (the best digicam created by Sony!) can save picture on TIFF file format. (i'm talking about saving on memory stick - another great&cheap creation!)

I've read on Steve's Digicams review (http://www.steves-digicams.com) that Sony DSC-S70, when saves the pictures in TIFF, also save a JPEG copy of this picture (i'm not talking about the "e-mail saving" format but about the "Uncompressed TIFF")!

For my opinion (but i think that everyone is agree!) this lead a 1Mb or more of memory space wasted, because any graphic program can convert a TIFF picture in JPEG format and i don't find any reason to have a redoundant picture in the digicam! I agree that some people may find this useful, but it's a better thing to have the possibility to disable this feature (in actual digicam firmware this is not possible).

Another few words about the Uncompressed-TIFF. I think that to have the possibility to save the picture not compressed with a lossy algorithm (as JPEG) is a great feature, but any graphic program i've used can handle the Compressed TIFF file format: with this format the file is compressed with LZW algorithm and you can have a picture of medium complexity 40% smaller than uncompressed format WITHOUT any picture quality loss!! This mean to use a 64Mb card to store 11/12 pictures instead of 7!! Note that LZW is used on DSC-S70 to save the picture on .GIF format (also known as "TEXT" format - another great feature).

None of the DSC-S70 competitor i know can handle the compressed tiff file format; this may be a good marketing point for Sony ("our digicams can save up to 40% of memory space without quality loss in image").

As programmer (my job is create automatic machines) i think that these features can be simply implemented on actual digicams with a simple and cheap firmware update (i think that Sony - one of the best electronic company in the world - leaved a backdoor on her products to let the service center to update the firmware!). Compressed TIFF-LZW is not a heavy computing feature (i tried to save a 2048x1536 picture with a PPC-604e running at 230MHz and the save operation requests about 5 seconds!!! i think that with actual processor is not sensed by the user!) - and the option to disable the savings of JPEG copy of TIFF captured image is a simple menu option... simplest to do than to explain!

Moreover a free of charge or a cheap firmware update obiouvsly increase the Sony's after sales and customer's care image!!!

Ok, friends! I've termined this post and i hope to read your comments or your suggestions about.

-- Francesco Piraneo G. (fpiraneo@libero.it), August 12, 2000

Answers

Hmmmm, it does seem odd to save a tiff & a jpeg. Unless it's done so they can more quickly display an image in the lcd viewfinder?

As far as tiff's go, it would take even less space to save the RAW CCD information. A Raw CCD file is only one third the size of an uncompressed Tiff, whereas an LZW is fully 1/2 the size or larger... Plus, the raw file is completely UNCOMPRESSED!

2048x1536 = 3,145,728 bytes of "raw" 8 bit values from the CCD. (remember color values from adjacent sensors are interpolated to produce 24bit color info.)

2048x1536 x 3 (24bit color values) = 9,437,184 bytes uncompressed Tiff

9,437,184 / 2 (LZW compression) = 4,718,592 bytes LZW Tiff

Plus the raw ccd is quicker during camera operation as no compression must be performed. It does have the slight penalty that the conversion(s) must be done later on the PC. Frankly, I'm all for uncompressed RAW CCD files. I think they should be the standard. It'd also allow for more innovation in PC based algorithms designed to massage the data and produce the full Tiffs. You'd be able to have customized control of how the color values are interpolated to form full 24bit data for each pixel. This is nothing new and is done on some of the high end models like the Nikon D1.

Good eyes, though!

-- Gerald M. Payne (gmp@surferz.net), August 12, 2000.