Sandman
In article <bb2q1a1upk1h9uadurrn9bdoll1vu99ch3@4ax.com>, Eric Stevens wrote:

The *only* point Lightroom loads the original file and applies the rendering chain in RAM is when you're viewing an image in 100% zoom.

Eric Stevens
Or when you export the image.

Sandman
Depends on how you export it. If you export it as a low-res highly compressed JPG, it can use the preview file. Chances are that it doesn't, but it certainly could, since the preview file *is* the current pixel data of the image.

Eric Stevens
So what happens when you want a high quality TIFF of the same size as the original file? Do you expand by resampling your low-res highly compressed JPG?

nospam
questions like this mean you don't understand how it works.

it *always* uses the original data. the cached previews are a speed optimization for the user interface.

Eric Stevens
I know that

Sandman
No, you don't.

Eric Stevens
but Sandman seems to disagree.

Sandman
With what, you're ignorant question born from your ignorance about the application? Well, yes.

Eric Stevens
That's why I asked him that particular question.

Sandman
No, you asked it because you have no clue how LR works.