Image quality of the 3100z's JPEG format?

Without knowing the make and model of the camera this is only a guess, but I would say it's either the image quality or image compression for the JPEG files.

Just about every camera stores photos as JPEG files (many cameras also offer other options, but JPEG is almost universal). JPEG uses a lossy compression scheme. This means that files are compressed to save space on your memory card. This compression throws away some data. Usually this is not noticeable. For example, if one point of a blue sky comes out a different shade of blue (but still close to its neighbors). It would be noticeable if a patch of sky came out green, however.

High image quality applies minimal compression, at the expense of file size. Low image quality applies more compression, saving file space but sacrificing quality.

Compression is the other way around. High compression saves file space at the expense of quality. Low compression gives higher quality at the expense of file space.

Whether these settings on your camera determine the image quality or the image compression, I can't say. You'll have to look in the manual for your camera.

If you require further assistance, please add a comment to this question and specify the make and model of your camera.

That depends on the picture format, resolution, and compression. RAW and TIFF images will take more space than JPEG images. Larger images will take more space than smaller images. Less compressed (better quality) pictures will take more space than more compressed (lower quality) pictures.

The only way to avoid any loss of image quality is to save the picture in DNG, RAW, or TIFF format. Any JPEG compression will always lose some quality, though the amount can be varied on most cameras. Depending on the make and model of the camera, the best quality (least loss) will be something like "Best," "Fine," or "Superfine." Consult your manual for the choices available on your camera.
If you need further assistance, please feel free to ask. But please specify the make and model of your camera.

The D3000 can store still images in two different formats. JPEG is a standard format, recognized by just about every image viewer and image manipulation program in the world. RAW is actually NEF (Nikon Electronic Format), a Nikon-proprietary format which incorporates almost all of the data captured by the sensor, without the processing of JPEG. JPEG files have the color balance, sharpening, contrast, and all the other camera settings done on the picture. With RAW files, you can change any or all of them and produce new JPEGs. In this respect the RAW file is similar to the original negative you get from processed film, while the JPEG file is like the final print. RAW files need special software for viewing and editing.

All JPEG files are compressed to save space. FINE, NORM, and BASIC represent different levels of compression. FINE does the least compression and takes up the most space, BASIC does the most compression and takes up the least space. Compression always loses some quality, so in general the less the compression the better the quality.

RAW+B simply stores each of your pictures as a RAW file and a BASIC JPEG file.

Having said all that, you should use only RAW or FINE settings. You didn't buy a SLR only to throw away picture quality, did you?

http://www.luminous-landscape.com/videos/download-videos.shtml

images are saved in the following format. Econ / Standard / Fine: JPEG (.jpg) Super Fine: TIFF (.tif) RAW: RAW (.mrw) Movie: Motion JPEG (.mov) Audio recording: WAVE (.wav) Symbols in brackets represent the file extension. Thumbnail data (.thm) is also saved for TIFF, Movie and RAW files.

No. IAS only supports pictures with standard, fine, superfine and Hypict, JPeg formatted pictures.

JPEG format storage is ideal for posting your photos to the Internet and for e-mailing them to friends. (It’s also useful for archiving when you've finished editing them and need to save storage space.) The compressed images still look good on-screen and contain a relatively large amount of information in the shrunken file. JPEG storage is great for maximizing space but not for maintaining image quality. If you want to get smaller files for archiving, use minimal JPEG compression (high quality/low compression). The ideal compression is lossless, which means there's no discernible drop in image quality even though the file size has decreased.

The details for each record mode are as follows: RAW: RAW data is unprocessed image data in its original state to which white balance, sharpness, contrast, color conversion and other processes have not been applied. CAMEDIA Master can be used to display RAW data and save it in other image formats. A RAW plug-in is also available for Adobe Photoshop which also provides the ability to process images in 32-bit color depth. TIFF: This is the highest-quality mode. images are saved as uncompressed data, which is the best for printing or image processing on a computer. SHQ: This is a high quality mode using the JPEG format. Because the compression rate is very low, high quality images can be stored. HQ: This is a high quality mode using JPEG format, with medium compression. Because the compression rate is higher than SHQ, file sizes are smaller. More images can be saved to a card. The file size can be changed in the 3:2 or Enlarge size mode as well as SHQ. 3:2 Mode: Ordinarily the image aspect ratio is set to 4:3. Due to change the ratio to 3:2, the picture size becomes 2592 x 1728 so that the image can be printed without losing the image borders at a photo lab. 3:2 can be set in the TIFF, SHQ, or HQ mode. SQ1/SQ2: SQ1 is used for resolutions above 1600 x1200 and SQ2 is used for resolutions below 1600 x1200. For both, you can choose high compression to reduce noise or normal compression to save more images.

The details for each record mode are as follows: RAW: RAW data is unprocessed image data in its original state to which white balance, sharpness, contrast, color conversion and other processes have not been applied. CAMEDIA Master can be used to display RAW data and save it in other image formats. A RAW plug-in is also available for Adobe Photoshop which also provides the ability to process images in 32-bit color depth. TIFF: This is the highest-quality mode. images are saved as uncompressed data, which is the best for printing or image processing on a computer. SHQ: This is a high quality mode using the JPEG format. Because the compression rate is very low, high quality images can be stored. HQ: This is a high quality mode using JPEG format, with medium compression. Because the compression rate is higher than SHQ, file sizes are smaller. More images can be saved to a card. The file size can be changed in the 3:2 or Enlarge size mode as well as SHQ. 3:2 Mode: Ordinarily the image aspect ratio is set to 4:3. Due to change the ratio to 3:2, the picture size becomes 2592 x 1728 so that the image can be printed without losing the image borders at a photo lab. 3:2 can be set in the TIFF, SHQ, or HQ mode. SQ1: SQ1 uses the highest compression for resolutions greater than 1600 x 1200. You can choose high compression to reduce noise or normal compression to save more images. SQ2: SQ2 uses the highest compression for resolutions less than 1600 x 1200. You can choose high compression to reduce noise or normal compression to save more images.