获取图片大小：

var originImage = new Image();

function GetImageWidth(oImage) {

    if (originImage.src != oImage.src) originImage.src = oImage.src;

    return originImage.width;

}

function GetImageHeight(oImage) {

    if (originImage.src != oImage.src) originImage.src = oImage.src;

    return originImage.height;

}

图片等比缩放：

function SetImage(ImgD, FitWidth, FitHeight) {

    var image = new Image();

    image.src = ImgD.src;

    if (image.width > 0 && image.height > 0) {

        if (image.width / image.height >= FitWidth / FitHeight) {

            if (image.width > FitWidth) {

                ImgD.width = FitWidth;

                ImgD.height = (image.height * FitWidth) / image.width;

            } else {

                ImgD.width = image.width;

                ImgD.height = image.height;

            }

        } else {

            if (image.height > FitHeight) {

                ImgD.height = FitHeight;

                ImgD.width = (image.width * FitHeight) / image.height;

            } else {

                ImgD.width = image.width;

                ImgD.height = image.height;

            }

        }

    }

}