(Quoted from GraphicsPro. Full article here.)

Converting a postage stamp into a billboard can be a daunting task. Because how an image is enlarged affects the final output quality, several factors need to be considered when increasing the size of an image. All too frequently, a lack of understanding of the sizing process produces unsatisfactory results at the printer. You can resize images in several different ways, so learning the ins and outs of image sizing assures the best quality reproductions and no time and materials wasted.

An important consideration in producing large images is the pixel capacity of the PSD (Photoshop) formats. High-resolution images can have a width and height of up to 30,000 pixels. Therefore, documents with image resolutions of 300 PPI can produce a maximum image size of 100 inches. If the printed image needs to be larger, the file needs to be saved as a Large Document Format (PSB) with a width and height capacity of 300,000 X 300,000 pixels. PSB files can be exported as TIFF files for compatibility with other software.

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