Optimising Pixel Graphics for Print

Pixel graphics are multicoloured images or photos composed of individual pixels (picture elements). The pixels are arranged in a grid, hence the term "grid graphics" (sometimes called "raster graphics"). Each pixel is assigned colour information, the sum of which produces the picture. With Spreadshirt, pixel graphics serve as a template for digital printing. In order that we can achieve the best possible result in printing with your graphics, please bear in mind the following tips:

Requirements for your pixel design

  • PNG, JPG, BMP or GIF file format
  • Maximum file size 10 MB
  • Image resolution at least 200 dpi
  • Maximum size 4000 x 4000 pixels
  • Design is isolated

Optimising image resolution

Photos or graphics in PNG, JPG, GIF or BMP formats consist of pixels (picture elements) arranged in grid form, each of which is assigned multiple colour information. The number of pixels in width and height also later determines the size of the print.

We print textiles at 200 dpi. The abbreviation dpi stands for dots per inch, and this provides information on the density of the picture elements. A graphic that is 1000 pixels wide, for example, produces a design 12.7 cm wide when printed at 200 dpi. A 2000 pixel-wide graphic produces a 25 cm-wide design etc.

A design with a low pixel width or height (for example, 800 x 600 pixels) cannot therefore be easily enlarged without loss of quality (for example to 12 x 10 cm or more). Because of the "missing" pixels, the print would in the end probably look out of focus and blurred. So only upload designs with sufficient resolution and number of pixels. We recommend 200 dpi and a maximum of 4000 x 4000 pixels, so as not to exceed the maximum file size of 10 MB.

If the resolution is too low, the pixels will be clearly visible.

Designs without background

Printing photos on T-shirts is extremely popular. Show photos to their best advantage and remove disturbing elements in the background – i.e. have the actual design without a distracting background. It is not enough to simply make the background white, because the white area will show in the print. It will be visible on both coloured and white products. The background of an image needs to be transparent so that our printers can ignore it. That's why it's important to save your cropped image as a PNG.

Design with background vs. cropped design.

No colour transitions with transparencies

To make sure that your design can shine on coloured products in its full brilliant glory, our printers spray a white top coat on the product before printing. Your actual design will then be printed on this layer. This is why your design must not contain any transparency transitions, meaning colour transitions from transparent to opaque. Why is this? In the semi-transparent areas, not only the product colour but also the white layer would shine through. Adjustment tip for advanced users: To create an effect similar to transparency transitions, use raster and halftone effects in your graphics program, such as "dissolve" or "dither”.

Consider colour differences in the CMYK and RGB mode

On a monitor screen, colours often appear brighter than on the printed shirt. To make the colours of your printed T-shirt look as intense as on the monitor, try the following:

  • Increase the brightness of your design. The printed product will never come out as brightly as the same image on the monitor. Please remember, that the monitor has its own light source whereas the print only reflects the light.
  • Increase the contrast and saturation of your graphics to a very high degree. What may look a bit ”too much” on the screen will look just right in print.
  • Always upload your graphics in RGB mode. Our software systems work with this colour scheme, and that's why smaller colour deviations are to be expected with RGB files when compared to CMYK files.

From left to right: Perfect – design too dark – contrast too low – saturation too low.