COLOR SPACE is the range of hues (e.g. blue, red), luminance (dark to light) and saturation that a digital device renders. There are two standard color spaces: RGB (red/green/blue) and CMYK (cyan/magenta/yellow/black).
Adobe RGB (1998) and sRGB are the defaults supported by digital hardware devices. Adobe RGB has a wider color gamut.
Inkjet printers convert RGB files to CMYK.
RGB to CMYK conversion is controlled by the print driver or imaging software.
Imaging software color management supports custom profiles for each paper/ink type.
RESOLUTION is the width, height and number of pixels per square inch (ppi) of a bitmap image. A pixel is a color/luminance/saturation unit of measure.
Digital devices record continuous tone images by slightly blurring the edges of pixels. Image sizing and sharpening are key for quality large size prints.
The iPhoneX records 3264 pixel x 2448 pixel images at 72 ppi images.
To resizing that image with Adobe Photoshop® open the image.
- Select IMAGE/IMAGE SIZE
- Deselect RESAMPLE and change RESOLUTION to 240 ppi or best resolution for the printer.
- Select RESAMPLE and constrain properies and resize either the horizontal or verticle dimension to the size desired. For instance if the verticle dimension is set to 8" the horizontal dimension will be 10.67".
- See PRINT SIZES for information about default image sizes.