The file format does not support animation

Portable Network Graphics (PNG)

Figure 14.74. Export PNG file dialog

The PNG format, a lossless format, supports transparency but doesn't support animation. So, you only can Flatten image, i.e merge layers into a single one, according to the mode you have selected for the image.

JPEG File Interchange Format (JFIF, JPEG)

Figure 14.75. Export JPEG file dialog

The JPEG format, a compression format with loss, doesn't support animation nor transparency. The file will be flattened and transparency will be replaced with the background color of Toolbox.

The file format supports animation

Multiple-Image Network Graphics (MNG)

Figure 14.76. Export MNG File Dialog

The MNG format is an animation format and supports 256 transparency levels (which, at last, are recognized by Internet Explorer 7). The dialog offers two options. Select Save as animation, since Flatten Image does not make sense here. Note that MNG images are not recognized by GIMP.

Graphics Interchange Format (GIF)

Figure 14.77. Export GIF File Dialog

The GIF format, less sophisticated than the MNG format, supports 256 colors and 2 transparency levels only.

The dialog offers you either Flatten Image or Save as animation. See the glossary ( GIF ) for more details about the GIF format.

If you have not transformed your image into a 256 colors indexed image before, this dialog will ask you choose between Convert to grayscale and Convert to indexed using default settings. Be careful: an indexed image undergoes a severe loss of colors and the added palette can give it a size bigger and a quality less than if it was saved as JPEG.