Post processing using DPP

[piyush]

Why simple correction in DPP like color correction/sharpness increases the file size to double or triple? I have noticed same thing in Picasa also. Am i doing some thing wrong? Not sure but all the files were 1.5 to 2 mb and after batch processing, it becomes 3 to 4 mb and  some of them become 6 mb too.

[Bob Atkins]

I guess you are taking about JPEG files here. JPEG is a compressed format. When you open the file it's uncompressed so you can work on it and when you save it it's compressed again. The compression is lossy and the harder you compress (i.e. the smaller you make the file), the more loss you have.

The simple explanation is that the files you are opening are more highly compressed than the files that DPP saves.  DPP has a default compression, but you can change it if you want to.

Also sharpening will slightly increase the amount of detail in a file, which means it will be slightly larger at any given degree of compression. However it wouldn't double or triple the file size, so I suspect it's simply a matter of different degrees of compression.

[KeithB]

Or if DPP is reading a RAW and outputing a TIFF, there may be a large increase in filesize since the RAW file only has a single "chunk" of pixel data, while the TIFF has 3 one each for R, G, B

[Bob Atkins]

True, but looking at the file sizes, its not likely that TIFFs are involved. The numbers (2-6MB) suggest JPEGs.

[piyush]

Oh yes, That's true Bob. I am using Large-Normal setting on Canon 400D (XTi) which comes to somewhere around 2 mb for each of the files. I got it. Thanks for the explanation. I will look into the compression in DPP. Thanks again.