Here are some tips for printing poster-sized or larger versions of our SDO images:
- When printing a large poster-sized image, you want to have an image resolution of about 150 dots per inch (150 dpi). (For printing in a publication, you want a resolution of 300 dpi.)
- For best results, begin with SDO images at 4096 x 4096 pixel sizes. These can be found in our AIA/HMI Browse Data area here: http://sdo.gsfc.nasa.gov/data/aiahmi/ Select the date, telescope, select Archive for display and 4096 x 4096 for resolution. You can then download the selected images for the selected time period with one click. The images are downloaded to your machine in a zip archive that you open to create a directory of images. You can also select single images using the browse directory at http://sdo.gsfc.nasa.gov/assets/img/browse/.
- Once you have an image, you already have enough pixel resolution to print a copy at 25 inches x 25 inches at 150 dpi.
- If you want to print a larger version you must first resize the image. We have used Photoshop and Gimp, but any equivalent image manipulation software program should be fine. In Photoshop you would use the Image Size menu. Type in the size you want while setting the resolution to 150 dpi. (You can use higher resolution, but the difference in quality will be hard to see.) In Photoshop, make sure that the options for Scale Styles, Constrain Proportions and Resample Image (preferably using the Bicubic Smoother method) are selected. In Gimp you would select the Scale Image menu, enter the new size and resolution, and the interpolation method.
- We have printed SDO images up to 8 x 8 feet with very crisp, well-detailed results using Photoshop.
We found another printing approach that looks great. Some inkjet plotters with appropriate inks and materials can print out posters using translucent (semi-transparent) paper. The results are impressive when hung in a sunlit window. Here is an example of some SDO images lit by indirect light: