Export file size

[TobyTucker]

I am having a brain fart moment about exporting different file resolutions in lightroom. I seem to remember setting up two distinct presets for exports. The first was a finals export that was jpeg (sRGB) @ 1'' quality, no resizing at 3'' ppi. This would yield a file size for me of about 7.5 megabytes. I then have a preset for uploading to an online image hosting site at a lower resolution. This preset is for jpeg (Adobe RGB) @ 1'' quality, no resizing at 15' ppi. This is giving me a file of about 7.2 megabytes. Shouldn't this file be at least half the size the 3'' ppi one? I seem to remember these files being a lot smaller. Not sure what I am missing here.
I tired setting the quality slider to 7' and the file dropped to 2 mb.

What am I doing wrong or not understanding here.

If I open the same file in photoshop and save it as a jpg with 12 quality at 3'' dpi it is 7.5 mb. If I resize the image to 15' dpi and save a jpg with 12 quality, it is a lot less.

Weird...or is it me??

Thanks,
Toby

 

[Halfje-Bruin]

The DPI/PPI is just a number and has nothing to do with the actual number of pixels. To reduce the file size you have to decrease the quality setting or resize the image.

 

[Mark Sirota]

First, you mean PPI, not DPI. You used both in this message.

Second, PPI is irrelevant unless you are also resizing and specifying your dimensions in inches (or centimeters). If you're not resizing, or you're resizing and specifying dimensions in pixels, then PPI is just a meaningless piece of metadata.

You need to check the "Resize to fit" box in the Image Sizing section of the Export dialog, and specify some smaller dimensions if you want a lower-resolution file for posting online. And for posting online, you specify your dimensions in pixels -- there's no such thing as inches (or centimeters) in that medium.

One more unrelated thing -- don't use Adobe RGB for posting online. Most browsers are not color-managed, and Adobe RGB colors will look desaturated in that environment.

 

[Brad Snyder]

One more unrelated thing -- don't use Adobe RGB for posting online. Most browsers are not color-managed, and Adobe RGB colors will look desaturated in that environment.

Mark, while I quite agree with this statement in general, perhaps Toby's hands are tied here. The online hosting/print fulfillment site I use, requests that images be uploaded in AdobeRGB. I'm not entirely happy about this, because, of course, the display images are a little flat, and desaturated in the web view. The fulfilled prints are fine. The site does take care to note to clients that these are small fast web views and prints will be much higher quality. (I've never had a single client complaint [at least on this issue]).