There's no loss of image quality with bitmap files - even when they're compressed.
The JPEG file format is perfect for photographs as most of the detail is retained and the file sizes are massively smaller than bitmaps. However, it's a "lossy" format which will lower the quality of the image a tad and introduce some unwanted artefacts. Having said that though, most folks will never notice so it's a perfect format for the average home user.
Professional photographers and graphic artists nearly always work with bitmap images.