Post Editing

[gstephens]

I have a Nikon D-200 and when I post edit (Picasa) and enhance the contrast and color etc, the file sizeincreases around 15 to 20 percent. I purchased a Canon G9 for my son the same post editing enlarges the files 200 to 300 percent and more. Some of the original files are around 4,800 KB and swell to over 14,000 KB. Is this normal?



Thanks . . .

[JimC]

How are you saving the files?

Picasa doesn't modify the original files unless you save or export the images. Instead, it just keeps track of the changes you previously applied and reapplies them each time you view the image.

But, if you save or export the image, the file size you get is going to depend on the type of file you save. JPEG is the most common type (because it's compressed to give you smaller file sizes). If you are using JPEG, the amount of compression being applied will impact your file sizes.

If you have the JPEG quality settings at 100% (which represents the least amount of compression being applied), that's going to result in much larger file sizes than a lower quality setting (probably much larger than the originals if you tried to set it that way). You'll find a setting for jpeg quality somewhere in Picasa (but, by default, it it's probably using a setting of around 80%, which really shouldn't increase your file size if you're saving in jpeg format). I'm not where I can look at it right this second, but you may also see a jpeg quality slider come up at the same time you save an image if you select jpeg.

[JimC]

P.S.

If you want to read more about the differences in file types and jpeg compression, see this October 2004 Tech Corner article by Mike Chaney:

JPEG Images: Counting your Losses

[JimC]

Here, I booted into Windows and loaded Picasa to see where the option for quality was.

I don't use the Save button in Picasa if I want to use the image somewhere else. I use the Export Button (bottom right button in this screen capture). Note the Quality Slider you'll see. That impacts the file size you get.

I've got it set fairly high (but still lower than the maximum choice in the drop down list). That's why it says "Custom" with 95% Quality. You can select a lower quality or higher quality than that via choices in the drop down list.

You probably have it set to Maximum (which would generate the largest file sizes because it would have the lowest compression).

[gstephens]

I do export at the maximum quality for both the Nikon and Canon files. Can you think of any reason the Nikon (D-200) exported file is increased around 20% and the Canon (G9) exported file is around 200-300% larger?

[JimC]

The G9 may have been using higher JPEG compression (higher compression = smaller file sizes = lower quality) for it's files at the quality setting you had set in the camera.

[gstephens]

You are correct . . . the G9 is a 12.1 megapix and the camera was set to around 8 megapix. The D-200 was set at the maximum just short of RAW.

Thanks for your reply and Thank Youfor this website . . .

gstephens

[gstephens]

I exported the files again and set the Size to "Original" and the Quality to "Custom 95%" and the file size increase was approx 20%. My son was in Tokyo forover three weeks and snapped off around 1,000 pics. The total of all the original files was 2.6 GB and swelled to almost 7.5 GB post edit. I'm am smiling once again due to your knowledge.

Thanks Again . . .

gstephens

[JimC]

No problem. Unless you plan on editing them in another application (or printing them at very large sizes, you probably don't need 95% either (even lower would work OK).