Digital printing has revolutionized the sign industry. Current printers can reproduce an image at 1440 dpi (dots per inch) at virtually any size. But they are worthless if the original image is of low resolution. We define resolution using pixels. A pixel is commonly thought of as the smallest individual unit of an image (tiny dots if you will). If the pixel content is low, the image will look fuzzy. Anyone that has blown up a picture in a popular program like Adobe Photoshop has experienced the pixilation of an image. The most common way to express the resolution of an image is via two integers: the first is the number of pixel columns or width and the second is the number of pixel rows or height. Another common way to express resolution is by giving the total number of pixels in the image (usually expressed as megapixels). It is determined by simply multiplying the pixel columns by the pixel rows.
Most typical file formats such as bmp, jpeg, png, etc. will give the physical image size. This is done through DPI. For raster images (those images in rectangular pixel format DPI means the number of pixels printed within one inch horizontally and vertically. For example, if you have an image expressed at 600 by 300 (or 1.8 megapixels) and you want to print at 300 dpi, the image would need to be printed within two inches by 1 inch (you divide 600 x 300 by 300 dpi) a very small image to get the needed resolution. The bigger you print the same image, obviously, the lower the amount of dots per inch. A 20 by 10 inch print of the same image would be only 30 dpi. Try to imagine how bad the quality would be if you had only 30 dots for every inch.
We commonly have customers uploading 600 x 300 jpeg images of the family dog, say, and ask us to put it on a vinyl banner 4 by 2 feet, for example. We refuse to print a sign with less than 300 dpi, because we know our customers will not be happy wth the quality. If we enlarged this image to fit the sign, we would get a sign with 12.5 dpi (only about 12 dots per inch).
We need to help educate so you will know that we are not trying to aggravate or, worse yet, price gauge when we ask for a better quality image. Believe me, we only do this so the customer will be happy with the final product. I always feel bad when I have to disturb a customer. I understand the buyers position. They want quick results with minimal effort. But customers have to take a proactive role, because once and a while, a sign company will go ahead and print a borderline or low quality image. We wont do that we insist on quality which sometimes makes the customer think we lack some mysterious technology that our competition has. There have been those frustrating times when a customer will tell me they know of a local sign company that will print their sign with the image as is. And then they hang up miffed.
If we cannot get a higher quality image we need to convert the file to vector format. This format allows us to enlarge the image without loss in resolution. In fact, we have a full time graphic person that can do this rather quickly in some cases. We usually try to do it gratis for our customers, but sometimes we have to charge them. It is awkward because the customer does not always understand. Some even suspect we are attempting to add on frivolous charges. We want them to understand why!
But I also have to caution customers. Some sign companies will charge high prices for art work. Converting a diagram or clip art to vector format can be very cheap about $10. But poor quality photographs require the artist to reproduce the file as a graphic drawing in detail. It takes time and most companies will understandably try to recoup their costs. But you should not be charged more than about $30 an hour and photographs rarely take more than 2 or 3 hours to convert.
