How to select a resolution that best meets your rendering needs

When transitioning from traditional mediums (paper, pencil, patterns, etc) into the world of digital applications, you’ll eventually need to know what pixels and resolution are. In digital imaging, pixels are small squares of color and when arranged together, you get an image that can be viewed and saved.

Resolution is a measurement in pixels for the width and height of a digital file (image) or device capable of displaying digital files (monitor, smart phone, etc.) and is intended only for the digital world has no correlation to any real world measurements.

So how do you know which resolution is right for what you need?

The truth is there isn’t any single answer to “what resolution should I choose?” Resolution selection depends on a number of factors, including:

• Project or source file(s) used (vector graphics, raster textures, etc.)
• Medium of display (monitor, projector, print, billboard, etc.)
• Purpose of viewing (checking designs, quality review, marketing, etc.)
• Before knowing resolutions to choose, you’ll need to consider PPI & DPI

PPI

If you’ve ever worked with applications like Adobe Illustrator or Inkscape, you’ve likely seen PPI used when exporting images. PPI — pixels per inch — defines the pixel density of the resulting image, typically used when exporting vector graphics (in inches) to raster graphics (in pixels).

Exporting higher PPI values means more details in the image but it also increases the file size, so knowing what value to choose depends on what you’re exporting the image for.

Exporting Graphics for a Website
You’ll want to keep file sizes small for web graphics, so stick with 72–150ppi or use an exact resolution if you’ve got a design to follow with a known maximum image size.

Exporting Graphics to View on a Monitor
Most display devices do not have extremely high resolution requirements for proper viewing — 4K TVs are only 3840x2160 pixels — and so a value between 150 to 300ppi will work well for viewing on a monitor or screen.

Exporting Graphics for 3D Textures
When exporting vector graphics to be used in 3D design applications like CLO or VStitcher, you’ll want to choose PPI values that provide enough detail but are not too high, otherwise the file size becomes quite large and can slow down your application.

Selecting a value between 300 to 600ppi will give more than enough data for typical style renders. If you need to do any extreme close-ups on the graphic, you might need to do test renders to see if it’s sufficient, and if not, export at a higher PPI.

Rendering 3D to View on a Monitor
In this case, you don’t need to think about PPI at all since you’re not converting a physical dimension to a digital one. All you need to consider is what the maximum resolution is for the monitor on which you’ll be viewing your image.

For example, if you’re viewing renders of your designs on a 4K TV in a conference room with your team, then anything beyond its maximum width (3840px) or height (2160px) is a waste of time to render. If you wanted a square image, then you should choose something equal to or under 2160x2160 pixels.

If you need closeup shots (like a button or tag) it’s always faster and better quality to move your camera and render a second image than it is to render at an extremely high resolution and crop the image later.

DPI

So far we’ve only talked about the digital world, so what about those of us who work in the real world? DPI — or dots per inch — is a measurement of the number of “dots” that can fit into one square inch. Dots can represent both methods of printing (ink droplets, laser points for toner adhesion) and scanning (photo receptors).

Scanning Materials for 3D Textures
When scanning materials to be used as textures in 3D designers, it’s best to scan at the highest DPI available, do your re-touching work and then save out a smaller copy. This way, if you need more information, you can go back without having to re-scan.

If you’re scanning your materials in using a DSLR or light-box solution like Vizoo, then simply set your camera to the highest megapixel values available (or compatible with your specific setup and equipment) for the same reasons.

Rendering for Print
Every printer / printing service will have documented DPI values to use for a variety of quality outputs and mediums. There is no general rule here, you need to render an image that matches the printer’s specifications. This can be done easily by:

Know what the DPI value of your printer (or service) is
Know what the real world dimensions (width & height) of the print will be
Use online image size calculators to convert these dimensions into pixel values. Use the pixel width and pixel height exactly to render your image.

To print a regular US paper ( 8.5" x 11" ) at 300dpi (common for inkjet printers), for example, you would need to render a resolution of 2550px by 3300px.

Works in Progress

Okay, so now you know what PPI and DPI are, where to use different values and how to consider them for final outputs, but what if you’re still working on the style?

Quick Previews
If you just need to see something quick, take whatever resolution, DPI or PPI you’ve decided is needed and cut it in half, maybe even in a quarter. Most of the time you don’t need the full size image to get a rough idea if you’re on the right track.

Internal Reviews
You’ve finished your work and now you need a supervisor to approve the design. This will be highly dependent on your company, but sometimes you will only need:

• Half the resolution to review, especially for high quality printing
• Only 4 of the 8 images the customer is expecting to see
• One high resolution image of the main view and lower resolution for the rest

Ultimately, as a rendering service provider we are happy for you to render everything at whatever resolution you want but from our experience working in film & animation, we know that sometimes, half is good enough to get the job done.

If you’re still unsure of what resolution is right for what you need, start by figuring out whether your images will be used for viewing on a monitor (PPI) or if they will be printed (DPI) and then review the categories above and decide what category suits your needs most.