What it the preview of a RAW file actually showing me?

When I open a RAW file directly from Photoshop CS a conversion routine starts up that lets me choose some options. On the left side is a version of the photograph. It that the imbedded jpg from the RAW file? (Fuji S2 camera). I ask because I've been surprised a couple of times by how much sharper the converted file is than the preview (seems to be).

Pete D.

Which raw converter are you using?

Guy

I'm using CS not CS 2.

no seperate converter, just what pops up.

What pops up if you don't have any other converter installed is ACR. I don't remember how it worked with CS but with CS2 the preview is of a small version but if you change magnification to 100% after a few seconds it will render a converted version with full detail. On a slow computer this may take a while.

Guy

Also take in mind that ACR does auto adjust for you. If you want to see what came out of your camera then click on the circle with an arrow head top right and unselect auto adjust.

What you are seeing is the actual RAW file data as converted by Adobe's default settings or those settings on your camera when the image was shot (as shot). This is not the jpg preview though it may match those settings. As you change those settings, it will change the photo in real time allowing you to make judgements on how the image should be processed. There are sharpening settings in the RAW filter as well that are being applied.

Following up on the RAW issue. Why does the image converted via Nikon Capture NX, for example, seem better in many aspects than the ACR conversion?

Howard, there are a lot of parameters used to create an image from raw data. The raw file contains readings from all photosites in the sensor array. In a standard Bayer-pattern array, that's 2x green sensors, 1 red sensor, and 1 blue sensor for each pixel. The process of converting this mosaic of individual readings into specific color and tone involves many decisions made by the software on how to weigh them, how properties of one pixel influence its neighbors (e.g. for smooth transitions and consistent color vs. better-defined detail) etc. so there is no simple 1-to-1 mapping from raw to TIFF or other image formats. Each algorithm makes slightly different decisions to arrive at its outcome.

Also, each converter has any number of user controls (brightness, contrast, saturation etc.) that may have different default values impacting the rendering of the image.

Guy