Raw to jpeg file sizes

[technofan]

Oki doki matey peeps,

Just a general question regarding file sizes. I have been snapping in jpeg (2.7mb) and raw (8mb) and converting the raw to jpeg (0.75mb). I would have thought that jpeg straight from the camera and jpeg processed on the PC from Raw would be similar in file size. Why is there an approximate 2mb difference? Anybody out there in the know?

Thanks,

Pete.

PS Have been playing with my new F4L 70-200mm lens this morning....coooool, it does pack a punch...the wife thinks I am trying to make up for something and that camera lenses are definately a 'male' thing

[severnsource]

Different compression algorithms. The amount of compression can be varied depending on the trade off you want between file size and loss of information; smaller file - more quality loss. Some designers algorithms seem to be more effective than others as well.

Bill

[technofan]

Thanks Bill

Pete.

[dejongj]

It also differs per photo...My RAW's are about 5mb, using ACR and saving at quality 10 Jpeg I end up between .7 - 1.8Mb...If I use quality 12 Jpeg they are at least 2Mb...

Try it at the maximum quality and then up the slider as maximum doesn't really mean maximum when saving as Jpeg...

[mr jones]

you've gotta remember that a raw converter can take much longer to convert a file than a camera, especially if you want the camera to take lots of photos in succession, therefore the raw converter can have a more indepth algorythm compressing the file more.

do you do alot of image manipulation after converting from raw? if so you may want to consider saving as a non lossy format such as PSD or .tif before finally converting to .jpg for distribution/developing. if you keep repeatedly saving .jpg file during manipulation you will loose image quality

[RobertP]

Using rawshooter my output jpegs on 'maximum' were 3 to 5 Mb in size from 8M raws. I now use 'higher' and get output files from 1.4 to 3M - more like the camera best jpg file sizes.

[mr jones]

rawshooter outputs to circa 25mb tiffs for me

[technofan]

Thanks Guys',

Informative stuff, I haven't done much work in RAW. The jpeg pictures I get are of such good quality that I've taken the easy way out....so far. However, when I eventually get out and about to take some 'serious' pictures I will work with 'lossless' formats. To that end what software is available that can recognise RAW files and provide excellent features (without breaking the bank)?

Ta

Pete Delaney.

EDIT: OK I found a free download of 'Rawshooter Essentials 2005' and I shall give it a whirl. I think from now on I shall stick to shooting in RAW format. Please feel free to tell me and everyone else what your favourite image processing software is (that supports uploading RAW images for processing). This is all good informative stuff

[RobertP]

I only use RAW when I want the best pictures I can get. It lets you make the changes you could have made on the camera settings - but after the shot is taken. If your settings were way off then all may be lost whatever you do in software but if your settings were only a bit wrong you can correct the exposure, white balance etc.

The reason for not using RAW all the time is that when you have taken a few hundred shots it can be a pain going through them all tweaking and processing. Rawshooter helps in that if you have a bunch of similar pictures you can copy the tweak settings from one to the rest of them. I shoot best jpg on the camera mostly and change to raw+small fine jpg if I think the situation warrants it. Having the camera jpg as well lets you see if your tweaks really did improve the image.

[mr jones]

Originally Posted by RobertP

I only use RAW when I want the best pictures I can get.

surely you want the best pictures you can muster all the time though?

[severnsource]

Originally Posted by mr jones

surely you want the best pictures you can muster all the time though?

A - not necessarily, you may only want low res pictures for web use for instance.

B - the best jpeg files aren't worse than RAW files in terms of quality. They will have been processed in certain ways that can be altered more easily from RAW files, but if you're generally happy with the cameras processing there is no real reason not to use jpeg files.

For another view on the issue try reading http://www.kenrockwell.com/tech/raw.htm

I've reverted to using RAW and jpeg because I've had a couple of lightly overexposed shots that could be corrected better from the RAW files, but most of the time I just use the jpegs.

[RobertP]

Originally Posted by mr jones

surely you want the best pictures you can muster all the time though?

RAW files are great but need the time invested to make them worthwhile.

Yes I want pictures I can be proud of. All the RAW format does is make it easier to sort out a problem after the event.

For family occaisions or whatever it's the subject and relevance that are far more important that getting the technical details spot on. In those situations I'd rather have easy jpgs that need no or little editing effort.

[tyefi]

I use RAW all the time... just batch process the 6*4 snaps using defaults i've optimised for the camera. I only take any time with 4 or 5 shots in 100 and overall find i can get more from RAW than jpeg.

[dejongj]

I don't understand all this RAW takes more post processing time, surely if you took the picture correct the first time it takes the same amount; i.e. nil...And if you didn't take the picture correct RAW is a heck of a lot quicker as you can adapt the basics which you can't in JPEG...

[severnsource]

Originally Posted by dejongj

I don't understand all this RAW takes more post processing time, surely if you took the picture correct the first time it takes the same amount; i.e. nil...

Well, it takes about 4 times as long to download the files onto your computer as you have about 4 times as much information to transfer. In order to get something useable from RAW you have to process it. You have to apply sharpening, exposure correction and colour balance, even if you do that as a batch process it will take time. Also you can't look at RAW files on a computer without extra software. JPEGs can be viewed on virtually any computer.

Originally Posted by dejongj

And if you didn't take the picture correct RAW is a heck of a lot quicker as you can adapt the basics which you can't in JPEG...

That is not true either. The standard things like changing contrast, brightness, saturation and colour balance can all be done on jpeg files, as can sharpening and all the other image manipulation processes. If you start off with a high quality JPEG file and don't repeatedly save as jpeg any quality loss will be minimal.

What you can't do with JPEGs that you can with RAW is change the colour space, remove excess sharpening and you have less freedom to undo overexposure, but if you have got the settings right in the first place these are not significant limitations.

Bill