File Type Options - JPEG

The File Type Options dialog is entered when you press Options in the Image Conversion dialog or the Send Image dialog. The dialog allows you to specify convert options for the currently selected image file format.

The available options depend on the file format. Here are shown the options for the JPEG file format.

You should only use JPEG compression for photographic and photorealistic images. The compression method has been developed and is optimized for photographic images. For other image types (computer graphics or text images the lossy modes introduce visible artifacts at the edges, and the lossless mode is less efficient than LZW compression (GIF or TIFF files).

Color Mode

Best Fit

Let EasyCopy determine the best color mode. This is the default. EasyCopy will choose the optimal color mode for the given image taking other current settings into account.

RGB

RGB means a 24-bit RGB image ("true color").
RGB is only available together with Lossless compression.

YUV

The YUV color space contains one luminance component (Y) and two chrominance components (U, V). This color space is used rather than RGB because it yields a better compression when JPEG is used.
YUV is only available together with the lossy modes of JPEG (Baseline, Sequential. and Progressinve).

Gray Scale

A gray scale image (256 shades of gray).

JPEG Mode
JPEG compression modes are Baseline, Sequential, Progressive, and Lossless. JPEG compression operates on continuous-tone images with one or three components (gray scale or color). Color mapped images are automatically expanded to RGB before JPEG compression. Apart from the lossless mode JPEG is a lossy compression method. A very high compression is achieved at the expense of an exact reproduction of the original image during decompression. The quality loss, however, is related to barely visible details, and annoying artifacts are normally only introduced when extreme high compression ratios are enforced.

Baseline

This is a sequential JPEG compression using the minimal subset of the JPEG standard. Any JPEG reader must be able to decompress a file using this subset.

Sequential

This mode exploits the full range of capabilities in the standard to produce a file that is decompressed sequentially.

Progressive

Progressive JPEG mode also exploits the full range of capabilities, but is decompressed progressively rather than sequentially. That is, each record of compressed data represents addition of details to the entire image. A major advantage of progressive decompression is that a version of the image holding enough details for identification is instantly available from the first few records of the file.

Lossless

Lossless mode is a highly efficient image compression method for photographic images. Opposed to the other JPEG modes it is decompressed into an exact reproduction of the original image.

Quality
You can use the slider to choose a number between 1 and 20 to specify the tradeoff between compression ratio and quality loss. This option does not apply to the lossless JPEG mode.

The leftmost slider position gives the highest compression at the expense of image quality, and the rightmost position gives the highest image quality and a lower compression.

Alternatively, you can use the drop-down menu to select image quality.

Low

(3)

Medium

(10)

High

(17)

Maximum

(20)

The compression ratio depends on the contents and size of the original image. Results in the range from approximately 50 : 1 (low quality) to 10 : 1 (high quality) can normally be expected.

Sampling
This specifies the sampling ratio for the YUV color mode's chrominance components. The option is dimmed for other color modes.

1:1:1	Y:U:V = 1:1:1
	All components are sampled equally.
2:1:1	Y:U:V = 2:1:1
	U and V are subsampled 2:1 horizontally.
4:1:1	Y:U:V = 4:1:1
	U and V are subsampled 2:1 in both directions (default).