Export JPG

JPG - Export

Joint Photographic Expert Group (JPG or JPEG) is technically a compression technique not a file format. But wide spread common usage has made JPG a file format for all practical purposes. The uncompressed contents of a JPG file will be a TIFF (EazyDraw’s implementation) or BMP bitmap image. The bitmap is compressed with a JPG compression method.

Since a JPG file is actually a JPG compressed TIFF file, all the parameters documented for TIFF exporting apply. Follow the TIFF link to learn about these parameters, especially the Dots Per Inch (DPI) parameter and size/quality related issues.

The LZW and Packed Bits compression methods documented in association with the TIFF discussion do not apply to JPG compression.

The key point of JPG compression is that it is "lossy" where the TIFF compression methods offered are "loss-less". This makes JPG useful for applications such a photographic-like images that are rich in continuous-tone, high definition (24 bit, or millions of) colors. An aggressive JPG compression will save size by skipping over the subtle aspects of the coloring and shading of the input image. In many cases this "loss" of information may not be detectable at the target viewing of the image. Especially if the ultimate output device is a computer screen.

The Compression numeric text box and corresponding slider are used to specify the degree of compression of the JPG output. By convention a value of 0 indicates no compression and a value of 1 specifies the most aggressive compression.

Select the compression and DPI value then use the save button to execute the save action.

Use the "Add Thumbnail Preview" button to install a custom icon for the exported file. The custom icon will be a small image of the exported drawing or graphics. If this button is not checked the macOS Finder will install an icon in accordance with the system settings and applications available on your system.

Proper selection of the correct export parameters depends on the ultimate use of the exported file. It is usually best to determine settings by experimenting, possibly with test files. Test first with high compression, viewing on the ultimate target medium. There will probably be unacceptable defects in the image. Decrease the compression value (go to 0.5 to begin a binary search) and recheck, continuing until defects are barely perceivable.

In many cases care in choice of the compression value will result in very small image size with fully adequate viewing quality. This can be especially important for web graphics that require communication over finite bandwidth networks.

In some cases recipients software applications may require JPG file format. If loss-less image quality is required, just set compression to 0, and pretend that JPG is really a file format.

The Antialias check box selects the use of macOS’s antialiasing algorithms during preparation of the image. In some cases it may be best not to use this capability. If antialiasing is used when viewing the image, it would be applied twice. If you need exact control over the color of each pixel be sure to turn off antialiasing as it will modify individual pixel color on color contrast borders.

Interpolation is applied to Bezier paths during preparation of the image. This normally has little affect on the image. If exact control over placement of pixels of lines and curves is needed select no interpolation. There are 3 levels and an automatic selection.