1. Why are my images saved as .jpg?

2. Is there a difference between a JPG and a TIF or RAW image?

3. Is there a way to minimize loss of quality in a JPEG?

4. I have two JPEG images taken at the same quality. Why do they have different sizes?

5. How much can the JPEG format compress an image?

6. How many pictures will fit on my internal memory or memory card?

1. Why are my images saved as .jpg?

JPG or JPEG, pronounced "jay-peg", stands for Joint Photographic Experts Group, named after the original creators of the standard, and is used to compress images. Mostly all digital cameras use the JPG standard for compression because it is the best quality to image size standard for use with photographs and paintings of realistic scenes.

2. Is there a difference between a JPG and a TIF or RAW image?

JPEG is "lossy" format, meaning that the decompressed image looses some quality when compared to the original image. However, these losses are minimized by the complex algorithms employed, thus making JPG the default standard for digital cameras due to the flexibility and greater compression that is possible with this format. JPEG is designed to exploit what the eye can see, notably the fact that small color changes are perceived less accurately than small changes in brightness.

TIF or TIFF stands for Tagged Image File Format and is a "lossless" format, meaning that compression may be employed but no quality is lost after decompression. The TIFF format produces an image size that is much larger than that of a JPEG and is therefore not as widely supported by digital cameras.

A RAW file is one that has not been compressed at all, thus resulting in very large sizes. Not all digital cameras support RAW files, which can have many extensions depending on vendor, due to the large amount of memory that they consume.

3. Is there a way to minimize loss of quality in a JPEG?

One of the many useful aspects of the JPEG format is that the extent of lossiness, or image degradation, can be adjusted. Mustek cameras provide several settings that allow for increased image quality resulting in larger file sizes. However, if memory and not image quality is an issue, camera settings can be changed from "Fine" or "Large" to "Normal" and "Small" depending on camera model and menu system used. The result is a trade between file size against image quality.

4. I have two JPEG images taken at the same quality. Why do they have different sizes?

JPEG compression works by compressing color. Thus the more colors present, the less compression will be employed.

A picture taken indoors without a flash will normally have a smaller size than a picture taken outdoors in the daytime. The difference in file sizes can be significant, even at "Fine" or "High" mode. The accompnaying Capacity Chart is therefore just a reference and not to be strictly compared too.

5. How much can the JPEG format compress an image?

JPEG can typically achieve 10:1 to 20:1 compression without visible loss. 30:1 to 50:1 compression is possible with small to moderate defects. 100:1 compression is possible, resulting in an image that is quite small while still containing enough detail and color to identify the subject clearly.

6. How many pictures will fit on my internal memory or memory card?

As previously mentioned, compression varies with subject and is therefore not standard. The provided capacity chart is only an estimate. You will more than likel take a different number of pictures than shown for your memory card size. The number can vary greatly, so there is no need to be alarmed or think that your Mustek product is defective.

Please click here to view the Capacity Chart. You can find your camera style by clicking the tabs on the bottom left corner.