Figure 1

This column is being written to demonstrate practical uses of CorelDraw for those working within the awards and engraving industry. For those new to Corel, I suggest concentrating on the basics from books, media, seminars or tutoring, with the aim of becoming productive as soon as possible. In other words, earn while you learn! And the most effective way to learn is by repeated use, gaining proficiency and then moving forward adding new skills. These articles try to focus on skills relevant to your needs. Procedure descriptions are somewhat generic due to wide variation in Corel versions. Consult your version documentation as needed.

A close friend in the recognition field has just acquired a new sublimation system. After years of learning the ins and outs of laser and rotary engraving using CorelDraw, he now faces a new learning challenge—working in a pixel environment using Corel PhotoPaint. The challenge he faces is the same as with any new software—what does he need to know to become productive as quickly as possible even in the most basic way.

The new gel inks now make sublimation more attractive to the smaller shops, where it is more likely for the printing heads to suffer from stretches of neglect while other projects are in production. That idle time which used to result in clogged heads no longer seems to be an issue, so I suspect there will be more interest in adding sublimation to the mix of offerings.

If I’m right, that means that my friend will not be alone in shifting gears from vector to pixel. To that end, I will spend the next few issues helping those just starting out with sublimation to identify the most useful features of PhotoPaint and how to work with them. Let’s start with understanding the difference between vector- and pixel-based images.

Pixel-Based Artwork
So what’s a pixel, anyway? The word is a shmushed version of the words ‘picture and ‘element’ and in fact, a pixel is nothing more than the tiniest particle (element) of a digital picture (any kind of digital image—photo, painting, illustration, etc.). This particle has some basic properties, the primary one being that a pixel is simply a square of a single solid color. Two other more technical properties are that the pixel has been increasing in power (memory capacity) and depth over the years.

Depth refers to the number of colors a pixel is capable of displaying. In the early days, a color pixel could be any one of 256 shades—these days it is in the millions of shades. In order for that to be possible, the pixel needed to ramp up its capacity to remember, and it did so by increasing the number of bits of information (memory) it could hold—the more bits, the more color capacity.

Images made from pixels differ radically from images made from vectors (paths). CorelDraw images are made up of outlines (paths, vectors) that the computer processes and remembers as math formulas and does so quite efficiently. Corel PhotoPaint builds its images within a simple grid of squares similar to a sheet of graph paper. The computer’s job in a pixel environment is more bureaucratic, like a census worker keeping close track of who lives at a particular address (what color is the pixel located at 447 across and 642 down).

File sizes of pixel-based pictures tend to be much larger than file sizes for vector images. For instance, a 5” x 7” color image suitable for good quality printing would be over 12 MB in size. A similar-sized vector image could be under 1 MB in size. That’s because in this particular pixel image, the computer has to keep track of 3,150,000 pixel addresses.

If there are that many pixels in a color 5” x 7” image then you can imagine that the size of one pixel has to be pretty small—1/300th of an inch, in fact, in the above example. Even though pixels are squares arranged in a rigid grid, they are so tiny that our eyes can’t see the square shape or grid, even at close range.

And that is the name of the pixel game—maintain a rigid grid of squares to make it easy to keep track of them, but make them so small that our eyes can no longer see them individually. In fact, a pixel could be a foot square, but if viewed from a quarter of a mile away, the square would no longer be identifiable to our eye, and the end result would be similar to the 5” x 7” image. Pixel size is unimportant. It’s all a matter of scale—pixel size to grid size in combination with viewing distance, enough so that our eyes are betrayed into seeing image only.

When we take pictures with our digital cameras, the first words that should come to mind are grid of pixels. Yet when we look at those photos on our computers or even print them out on our inkjet printers, we just can’t imagine we are looking at a rigid grid of squares of color, but in fact that is what we are seeing. That is important to understand, since it is that grid that we work with to improve, alter or manipulate images destined for sublimation.

Resolution
When we take a photo or scan artwork, it is generally advisable to capture as much information as possible. Therefore we want to have access to as many colors as possible—millions should do just fine—and we want a lot of pixels. Since a pixel is a solid square of color, then a lot of information means a lot of pixels accessing a seemingly unlimited color palette. The 5” x 7” photo mentioned earlier had a resolution of 300 pixels spanning one inch, which means its pixel dimensions were 1500 across (5” x 300 = 1500) and 2100 pixels down (7”x 300 = 2100). Multiplying the width times the height tells us how many pixels total there are in that image (1500 x 2100 = 3,150,000). Now that’s a lot of information!

The thing about capturing information is that you can always throw away what you don’t need, but you can never manufacture more than you first captured. It’s a lot like wilderness camping. You have to bring enough food with you, but if you bring too much, you may find it impossible to carry on your trip, in which case you can ditch some along the way. However, if you skimp on food to make the load lighter, you might starve to death. Likewise, too much information captured means large file sizes that may be impractical to haul around and slow to manipulate, but too little information can be severely limiting in terms of image dimensions and quality.

Now the easy thing to do is ignore resolution all together, forget about it, repress it. If the photo looks anything like Aunt Sally, then why bother with it. Hey, if you can live with that, then by all means skip this and move on to the next article. However, if you want some say in how Aunt Sally looks, then the first hurdle to get over in PhotoPaint is to learn how to control the resolution of any image you are planning to sublimate.

Capturing
Scanners are easy. Many scanners provide the option of simple scanning, in which case the scanning software decides the fate of the image, making assumptions about how you want to use it. But most scanners also have advanced scanning options, in which the operator can choose various aspects regarding the scan, including the resolution. On average, scanning at a resolution of 300 pixels per inch (PPI or sometimes seen as DPI) will provide enough information. However, if the original image is small and the plan is to make it larger in the end, then a resolution of 600 PPI or more would provide more information.

Most digital cameras also have settings that can be changed in terms of image quality, with settings such as average, high quality, super high quality, and in the better cameras—raw, which is the highest quality that a camera can produce. It is important to be aware that the higher the quality, the longer it will take for the camera to process the image and the fewer the images that will fit in the camera’s storage. I know that can be inconvenient, but what is worse is taking the perfect shot, only to discover later that the quality is low—a permanent condition that cannot be fixed.

The internet, friends, clients, clip art from CDs or DVDs or from software packages are all possible sources of imagery except that you have no control over the quality. If you do not understand resolution or how to evaluate and alter it, then you will have little control over the final results of the work that you do. It is very common for clients, especially, to provide an inadequate image, expecting miracles. A quick evaluation in PhotoPaint can keep such a situation from getting out of hand, wasting time and money.

How? Simple. Open PhotoPaint and go to File/Open and browse for the photo, etc. that you want to work with. Once it is opened in PhotoPaint, go to Image/Resample and a dialogue box appears containing information on width, height, resolution and file size along with the ability to make changes to those numbers. Much can be learned by studying this box, changing a number and watching the effect on other numbers. There are three boxes, Anti-alias, Maintain aspect ratio, Maintain original size, which can be checked or left unchecked.
(See Figure 1)

In the beginning, keep Anti-alias and Maintain aspect ratio checked, but experiment with checking or unchecking Maintain object size. Checking it preserves the original information captured by linking resolution to file dimensions. The 5” by 7” image mentioned above with the resolution of 300 PPI is possible to convert to 72 PPI without altering the color or total number of pixels in the image by automatically increasing the height and width to 20.833” x 29.167” when the resolution is changed from 300 to 72. Even though the size and resolution have changed, the image has not. Both are identical in terms of quality.

Unchecking that box allows the user to change the resolution and the image size at the same time. This does permanently alter the image once the OK button is clicked. If so, I advise saving the document with a new name (SaveAs) to preserve the original file, because once information is altered, it can’t be restored. Making the image smaller by, for instance, changing the 5”x 7”x 300 image above to 3” x 4.2” x 300 will not hurt the image quality much. However, enlarging that same image to 10” x 14” x 300 will start to have a negative impact on the quality of the image which I will address in my next article.

Try checking out a number of images by opening them in PhotoPaint and opening the Resample dialogue box to try to determine how much information the image contains. In my next article, we’ll look at other factors that can affect quality and file size, and learn how to make actual adjustments that can affect the quality of the image.