A method of self-adaptive conversion for images includes: calculating the degree of color saturation of each pixel of an RGB image and original grey value of each primary color component, and calculating a global gain value; calculating a total gain value of each pixel based on the global gain value and the partial gain value of each pixel; enhancing luminance of the white color component of each primary color component of each pixel based on the total gain value of each pixel, so to output an RGBW image. The present invention improves deviated color saturation to ensure display quality while elevating the display luminance when a conversion from an RGB image into an RGBW image.