People sometimes get hung up on DPI like it really matters. It doesn’t, at least not in the way you may think. The number of pixels matters. The scaled resolution of an image to print matters. DPI is just a setting and an indication of when scaling is required. Where I’m really going is to say an artist must be a craftsman with his tools and technology.
I get information from people all the time requiring image previews at a certain DPI. One client even required images at 72 DPI stating that it was for my protection – implying that a lower DPI image wouldn’t be copied or stolen.
The number of pixels is what is important. DPI is just a setting. You get it by taking the dimension of the image in an axis and dividing it by the desired print length of the axis. So if I had an image that was 3000×3000 pixels and I wanted to make a 10×10 inch print, 3000 / 10 gives 300 DPI. This is a good resolution for printing. I know from looking at the DPI that no additional scaling or interpolation needs to be done.
But what if I wanted to print that same image at 30×30 inches? In this case the DPI would be 100. I know that is too low. To print it well I should scale and interpolate it to at least 240 DPI. This is simple to do in Photoshop and Lightroom and various other tools are available to do it. So the DPI is really only useful as a metric to the person making a print or for a designer creating a layout. How did I know 100 DPI was too low? I have to know that. That is where I’m going.
What’s the use of even bringing it up then? Well, I believe it shows a certain lack of rigor or even understanding by the people using the digital products. Too many artists say “I’m not technical. I just do things by feel.” That is too simplistic in the digital world. It is great to say you’re more interested in the artistic outcome than the technology. I agree with that. But pixels and sensors and lenses are the tools and resources we work with to create. An artist has to be a craftsman who knows his tools well. He has to know when and how to scale a collection of pixels to create an excellent print. He has to know when and how to sharpen an image to make it look great without introducing artifacts of over sharpening. He has to know how to do black & white conversions. He has to know how to do color corrections and tone mapping to achieve the look he wants. These things are specific technical skills and require knowledge of what is being done and why.
I’m not saying an artist or craftsman must use the latest, best, most expensive tools. No, use the tools that you’re comfortable with and that work for you. But master them. Whatever your tools, you should be an excellent craftsman with them.