The technique of improving the performance of web applications by reducing the size of downloadable files, namely image compression. For using colored image with transparency has been applied the modified wavelet compression method, in particular while maintaining five, ten and fifty percent of the coefficients to reduce the file size of the compressed image while maintaining its quality. Format bmp was chosen as the source format to convert, because it stores the image pixel data in a simple two-dimensional array, and therefore takes the most memory on disk. Experimental researches were conducted, and they showed that the use of this method enables to reduce the image file size at least 47% compared to other common data formats of graphical images. This gives an opportunity to significantly reduce the load image files in web applications.