Render Settings Preferences - Image tab

In the Menu Bar, click Edit > Preferences, then on the left side of the dialog box, select Render Settings.

Image

Resolution - Sets the resolution width and height in pixels for images rendered to disk. Use the drop-down list to select from standard resolutions.
DPI (Dots Per Inch) - Defines the image resolution in dots per inch.
Size - Displays the physical image size in millimeters and calculates it using the resolution and DPI values.

Supersampling - Enable the increase of antialiasing quality. This may impact performance.
Stereo Mode - Options include Mono, Stereo, 5 Eye Stereo (five images), and 9 Eye Stereo (nine images).
Compression Quality - Sets the compression quality of an image by percentage. This only applies to image formats that support compression, such as JPG. For no compression, enter -1.
Export Options - Select the Export options you want:
- Export Image with Alpha Channel - Renders the alpha channel into the resulting image, if the file type supports it. You can select the alpha channel color separately.
- Show Rendered Image After Saving - Opens a separate window, showing the rendered image.
- Single Image Viewer Window - Shows only one image per window.
- Ignore Aspect Ratio - Squashes or stretches the rendered image and ignores the aspect ratio.
- Export to formats such as TIFF/PSD (32 bits per channel), EXR (16-Bit Float), and Multi Layer EXR/PSD.

Use these controls to set the start frame, stop frame, and frame rate for your animation. You can export a series of images or an AVI movie.