Preview quality

16/02/2009

The quality of the web to print previews depends on a few factors. These guidelines can help better understand why in some cases the preview of your design doesn’t look the same in your online catalog as it does in CorelDRAW.

Pixelation

Small sized templates can show some pixelation in previews. It may be caused by JPEG compression and inflated bitmaps.

Example

Web-to-print pixelationWeb-to-print CorelDRAW preview

JPEG compression

JPEG artifact is most visible in solid fills. It can manifest itself as a color distortion or pixelation. There is always a choice between the file size and the quality. JPEGs with 100% quality can reach many megabytes on a standard preview. Our web-to-print image generator dynamically adjusts quality between 70% and 80%. Anything smaller than 70% is small in size, but the artifact is too obvious. Anything larger than 80% is too big for fast loading and benefits only a few types of designs.

Bitmap inflation

A standard business card size is 91mm x 55mm at 300DPI. A preview image can be 3 times larger than the real size, so the bitmap resolution drops to 100DPI. Effects and bitmaps may appear pixelated at that resolution.

Output quality

Preview quakity is a separate issue from output quality. Files generated with orders (CDR, PDF, JPG) are rendered at the desired resolution that the designer has set inside CorelDRAW. However, users might think that the template doesn’t have the required quality because they see pixelation in the previews.

Color rendering

Working in print-ready colors (CMYK) may also result in some unexpected preview results. The reason for this is the fact that previews are in RGB color mode which is a color space used when viewing a file on a screen rather then on a printed surface. This automatic conversion sometimes makes the on-site preview look different then in CorelDRAW. Read more about color matching – monitors VS prints.

Example

Web-to-print CorelDRAW preview/

/

This template has a CMYK color space since it is for printing puposes. Its complex layered structure with custom transparencies makes it more sensitive to the color conversion.

/

/

/

Web-to-print on-site preview/

/

/

Converted to a RGB color mode by the system, the preview looks like this.

/

/

//

Solution

Use the Advanced effects rendering option in these cases.

See also: