This disclosure describes techniques for encoding data to compress image data to a reduced size. The techniques may be particularly effective in transcoding an image to a reduced size for transmission. An encoding device may transcode an image to an acceptable file size using bitrate control techniques that affect the entire image uniformly to transcode the image. For example, the encoding device may modify one or more quantization tables as a function of the near linear relationship between bitrate (R) and the number of zero-valued quantized transform coefficients to reduce the file size uniformly over the entire image. Alternatively, or additionally, the encoding device may transcode the image using bitrate control techniques that affect only specific localized regions of the image.