From Nexus Wiki
How To Convert Height Map Images To RAW Format
First of all, let me be clear and concise, I have tried many image editing software and so far I have only been successful with Photoshop CS5. You can download the trial of Adobe Photoshop CS5 at www.adobe.com.
This article will guide you through the process of converting an images such as a jpg or png file format to the raw file format.
The raw file format is used in height map editing in the construction set for TES IV: Oblivion. If you do not understand how to use the height map editor I recommend you put this guide on hold and learn how to use it, otherwise this guide is not for you. Each quadrant in a world space, take Tamriel for example, is exactly 1024 pixels by 1024 pixels. The height map image you are converting must have this precise width.
To begin, open Adobe Photoshop CS5. Once loaded, click file > open and select the height map image you wish to convert.
Once the image has loaded click image > mode and select Grayscale as the color type and 16 Bits/Channel.
You are now finished editing your image and may click file > save as. On the next menu change the format to Photoshop RAW (*.RAW), then click save. In the following menu change header to 0 if it isn't 0 already. Next change Byte Order to IBM PC and click ok.
A warning may pop up saying "Some image data (for example, printer settings) cannot be saved with this file format. Save anyway?" Click OK.
Your file has been successfully converted to the raw image file format and is now compatible for use with the construction set.
To open the file in photoshop, be sure the dimensions are both 1024, your channels count is set to 1, the depth to 16 bits, the byte order is IBM PC and the header is set to 0.
I hope this tutorial has been useful to you. Thanks for reading. Will create more articles after the release of TES V: Skyrim.