File Size With USM

I have noticed when I save one of my 7d pics in LR3.2, I have a file 3600x2400 at approx 6.3mb. When I move the pic into PSE7 and apply USM the same pic now is 3600x2400 and approx 1.29mb.
Excuse my ignorance but why is the file size reduced that dramatically just by the application of USM. I usually apply between 75 to maybe 150% depending on the pic, but, as an experiment I just used 1% as a tester and the file size was hugely reduced again. Just don't know why ?
BTW the radius is 1.5 pixels and the threshold is 0 if that has any bearing on it.
Many Thanks

What file format are you saving to from PSE? JPG? TIF? If JPG, what quality level?

Two things. It sounds like the default compression between the two are different. That would account for such a big change. Also, USM might reduce pixel level noise a bit allowing for more compression. That too would reduce file size.

gjl711 wrote in post #11697946
Two things. It sounds like the default compression between the two are different. That would account for such a big change. Also, USM might reduce pixel level noise a bit allowing for more compression. That too would reduce file size.

On the contrary, sharpening (and especially small radius, high amount USM) enhances detail and at the same time increases noise, which it can't differentiate from detail without human intercession. Both effects increase jpg size.

1. noise doesn't compress.
2. some apps use a 1-10 scale for jpg quality, others 1-12. same range, different numbers. you're not missing 2 levels.

Ok, thanks for your speedy replies all, sorry for not being more specific in my origional post. I save from LR at quality 100 ( max ) and 300dpi ( for me to print ) at 3600x2400 as a jpeg. I then go into PSE7, open my jpeg and add my USM. Then I 'save' re-neme the pic and the jpeg options box comes up, its already at the medium level ( pre set at 7 ) and I then click'ok' to send it to my folder to print.

I can see the reduction now between the 2 quality settings, but its only a 'high' in LR to a 'medium' in PSE7 and that seems a huge difference in file sizes.....

As was stated, noise and sharpening (which increases noise) will cause jpeg files to be larger.

The reason for this is that jpeg uses a compression system to make files smaller. The way it works is that if there is an area of pixels that are all the same color then instead of recording individual pixel data it just stores one value for all of the pixels in that range. But if there's a pixel of noise in the middle of that range then it has to be split up. Instead of "range 1 is blue" you get "range 1 is blue, pixel 1 is white, range 2 is blue" so it takes up a lot more space.

h14nha wrote in post #11698418
Ok, thanks for your speedy replies all, sorry for not being more specific in my origional post. I save from LR at quality 100 ( max ) and 300dpi ( for me to print ) at 3600x2400 as a jpeg. I then go into PSE7, open my jpeg and add my USM. Then I 'save' re-neme the pic and the jpeg options box comes up, its already at the medium level ( pre set at 7 ) and I then click'ok' to send it to my folder to print.

I can see the reduction now between the 2 quality settings, but its only a 'high' in LR to a 'medium' in PSE7 and that seems a huge difference in file sizes.....

When you bring up the Elements Quality level, it is only what it has been previously set to, which you say is 7. That is not maximum quality and has nothing to do with the Lightroom conversion.

So, the next time that dialog comes up, just move the level to whatever you want -- for printing higher is good. When you save that it will again be "sticky" until the next time you change things.

By the way, if you are interested in maintaining maximum quality for printing, you should consider what's called the "best practice" of opening the image in Elements as a tiff (or psd) to avoid jpeg compression until the very end of your editing process. Try the "Edit in..." function for doing this and keeping the edited version in Lightroom at the same time.

h14nha -
Read this to understand jpg compression in general and in LR in particular:
http://regex.info …room-goodies/jpeg-quality

tzalman wrote in post #11699558
h14nha -
Read this to understand jpg compression in general and in LR in particular:
http://regex.info …room-goodies/jpeg-quality

Thanks for the link, interesting reading and an easy descriptive layout for beginners like me to grasp the concept.

tonylong wrote in post #11699095
By the way, if you are interested in maintaining maximum quality for printing, you should consider what's called the "best practice" of opening the image in Elements as a tiff (or psd) to avoid jpeg compression until the very end of your editing process. Try the "Edit in..." function for doing this and keeping the edited version in Lightroom at the same time.

Tony, I see where you're coming from with this, but, if I set the PSE to maximum then I am limiting my storage on my hard drives yes ? A trade off in image IQ versus hard drive space ? To be honest I'm pretty pleased with the detail my prints are resolving at the moment as my 7d seems to eat up available GB's. I will however take up your advice about saving as a tiff in LR for pics I want to print, thanks.

krb wrote in post #11698465
As was stated, noise and sharpening (which increases noise) will cause jpeg files to be larger.

The reason for this is that jpeg uses a compression system to make files smaller. The way it works is that if there is an area of pixels that are all the same color then instead of recording individual pixel data it just stores one value for all of the pixels in that range. But if there's a pixel of noise in the middle of that range then it has to be split up. Instead of "range 1 is blue" you get "range 1 is blue, pixel 1 is white, range 2 is blue" so it takes up a lot more space.

Thanks, you've made whats a complicated system sound fairly basic.....

h14nha wrote in post #11700373
Tony, I see where you're coming from with this, but, if I set the PSE to maximum then I am limiting my storage on my hard drives yes ? A trade off in image IQ versus hard drive space ? To be honest I'm pretty pleased with the detail my prints are resolving at the moment as my 7d seems to eat up available GB's. I will however take up your advice about saving as a tiff in LR for pics I want to print, thanks.

The reason for for saving an "in-process project file" as a tiff is to avoid saving a jpeg multiple times. The causes re-compression -- the jpeg compression takes place automatically and can over time degrade the image qualtiy.

As to how much, that depends on different factors. You could save a few times at high quality and see no bad effects, but a lot of us who have been doing this for a while can testify to unpleasant surprises we encountered before adopting this workflow practice.

And, that would be especially true if you saved at lower than the highest quality level.

Now, yeah, a tiff eats up drive space and a high quality uses more than a lower quality. Well, it's down to choices.

One good "safe" choice is to open the image in Photoshop from your Raw converter without converting to a jpeg -- it will open as either a tiff or psd, then do your Photoshop processing and decide -- how important is it to retain this project with the processing such as layers intact, or am I "done" with it? A jpeg won't retain layers, so if you want to preserve layers you need a tiff or a psd. An 8 bit tiff is good if you are done with "major" adjustments and will retain your layers.

But, if you are finished with the image and all you want is a final output, a high quality jpeg can print fine and you can resize for the Web without losing a lot since you are in control of the quality.

I myself try to avoid a high volume of such things by doing just about all my processing in my Raw processor.