elValue === undefined || largestPixelValue === undefined) {
            let src = jpegOutputData.getComponent(0).data
            let srcIdx = 0
            smallestPixelValue = src[srcIdx]
            largestPixelValue = src[srcIdx]

            for (let y = 0; y < jpegOutputData.height; y++) {
              for (let x = 0; x < jpegOutputData.width; x++) {
                let val = src[srcIdx++]
                if (val > largestPixelValue) {
                  largestPixelValue = val
                }

    