You can read the images into memory once at the beginning of the program and then use the drawImageFromBuffer function.
/**
* @brief Draws an image on the screen using the contents of the memory buffer.
* @param buffer A pointer to a buffer containing image data in either bmp or png format.
* @param x The x-coordinate at which the left edge of the image will be drawn.
* @param y The y-coordinate at which the top edge of the image will be drawn.
* @param bufferLen The size of the source image buffer in bytes.
* @return Returns true if the image was successfully drawn on the screen.
* @details
* This function draws an image on the screen using the contents of a buffer into which
* either BMP or PNG raw data has already been read. The contents may have come from a
* file on the SD card or have been statically declared in the code. The image should be
* no larger than the V5 Screen, that is, a maximum of 480 pixels wide by 272 pixels high.
* The top/left corner of the image is placed at the coordinates given by x and y, these can
* be negative if desired.
*/
bool drawImageFromBuffer( uint8_t *buffer, int x, int y, int bufferLen );
or, if the images are small, embed them directly into the code, see this example.