Converting Graphic Images

Comparison between Bitmap Images and Vector Graphics

Bitmap Images

Concept: Bitmap images are made of a series of dots or pixels.

Advantages
• Smooth representation of photographs.
• Easy to apply filters and effects.
• Suitable for producing photo-realistic imagery.
• Extensive clipart and library images online.
• Direct format for digital pictures.
• Easy to convert between color systems.
Disadvantages
• Large in size.
• Loss of quality if resized.
• Bitmap to vector conversion is difficult.
• Images can't be manipulated individually.
• Logos are not reproducible in high quality.

Vector Graphics

Concept: Vector images are described by mathematical formulas.

Advantages
• Very small size.
• Completely editable.
• Resizable without loss of quality.
• Easy to convert to bitmap image.
• Vector files can be manipulated individually.
• High quality logos, fills, gradients and outlines.
Disadvantages
• Cartoon-like appearance.
• Hard to change color systems.
• Expensive software and hardware.
• Unsuitable for producing photo-realistic imagery.

Conversion Between Graphic Image Formats

Conversion between graphic image formats is the process to convert the bitmap image into a vector graphic format and conversely convert the vector graphic into a bitmap image.

Bitmap to Vector Conversion:

Bitmap to vector graphic conversion is a difficult highly technical and time consuming task. There is no program or utility which can "vectorize" the image you have at hand into perfection simply because the software doesn't know the end result that you need to arrive at. Some software programs that create bitmap objects, like Adobe Photoshop® can save a file in a vector format, but all that is really happening is that the software creates a vector envelope and places the bitmap object in the envelope. The object continues as a single bitmap image and cannot be edited in a vector software program. There is still no vector art inside the Photoshop vector file saved.

Some vector software programs contain a Trace feature that attempts to create vector objects from bitmap images. These functions examine the bitmap for areas of a solid color, and attempt to create a series of vector lines to approximate their boundaries. These functions rarely produce useful results for the Graphic Arts professional, as most bitmaps contain occasional ragged pixels and the function tries to faithfully re-create the ragged edge.

Professional graphic designers usually trace the image by manual process, which gives absolute control over the objects newly created.

Vector to Bitmap Conversion:

Vector images can easily be converted to bitmap images. To make this conversion, your computer need only go through the steps of displaying the vector image on your screen while recording which pixels are used, and in which colors. But there is no "Conversion" process for transforming bitmap files into vector files. There is no "line" or "object" information in the bitmap file.

The most common reason for wanting to convert a vector to a bitmap would be for use on the Web.