Shooting JPEG or RAW and convert to JPEG

[pharris]

Hi all

I have just got a New 10D and have been playing with the settings, one thig I have noticed is that if I shoot in JPEG Large Fine the images are around 2 to 3 meg in size but open upto 18 meg in PS but idf I shoot in RAW and and use FileViewer to convert to JPEG the files are around 5 meg but still open up to 18 meg in PS.

Does this mean that the RAW conversion is of a lower compression level than the in camera processing, or am I missing something.

Thanks for any in-put.

Paul

[Monito]

RAW is lossless compression. JPEG is lossy compression.

[scottbergerphoto]

A Raw file is all the linear sensor data with the EXIF information so it can be displayed on your computer by a conversion engine. A jpeg has already been converted and compressed with some loss of data. To see the difference, take two pictures of the same subject and lighting one as jpeg and one as Raw. Open up a raw file and convert to 16bit tiff. Open the tiff and jpeg in PS, open up Levels ( Control-L)and compare to two histograms. The spikes ang gaps in the jpeg histogram are missing and condensed data.
Scott

[Eric DeCastro]

oh baby I like it RAWWWWWWWWWW.


I only shoot raw, unless i'm shooting for something for ebay.

[pharris]

I do understand about RAW giving a higher quality picture than JPEG but my question was about the difference between shooting in JPEG and Shooting in RAW and then converting to JPEG, why is there such a difference in the file size.

Paul

[Eric DeCastro]

jpeg is compressed files.

[karusel]

You mean the difference in JPEG filesize? Because in-camera jpeg converter uses a differend compressing algorythm than the raw converter on a PC. The 18 megs in photoshop is simply the uncompressed filesize, now I forgot this bit, so I will assume there are 3 channels for RGB values, hence 3x6mpixels=18,1 megs.

Anywho, knowing this to detail will not contribute to improving your photos ;)

[ToriEm]

Check out the thread titled "Canon 10D JPEG Compression". It was helpful to me.

[jftphoto]

Hey will the size of the file mak a diffrence in a eaw or jpeg. like 8 megs vs. 11megs vs 16megs vs. 22megs.

[Jim_T]

Using a RAW converter to create a JPEG from a RAW file does produce JPEGs with larger files sizes. Obviously there is less compression.

But other than the apparent numeric difference between the file sizes of the JPEG out of the camera and the RAW converted JPEG, there is no visually percepable difference in how the images will look on your monitor or when printed on paper..

[hmhm]

An image can be compressed to JPG at a range of compression "lossiness" levels. Whenyou save to JPG from Photoshop, they offer you a range of levels, with the lower settings yielding smaller file size and greater loss of detail, and the higher settings yielding larger file sizes and lower loss of detail.

I've never tried the experiment myself, but it wouldn't surprise me if a RAW file converted and saved to JPG at the highest quality setting yielded a larger JPG file, one closer to the original image quality, than the JPG yielded by in-camera compression, even at the highest image quality in-camera "fine" level.
-harry