When evaluating image resolution, separate three pieces of information: the pixel size of the file, the physical measure in which it will be used, and the pixel density at that measure. Just because a file says "300" in its setting does not mean it will be printed clearly at any size. Proficiency is evaluated based on the measure of actual use.
PPI is how many pixels an image contains in one inch; DPI describes the dot density of the printing device. Although they are used interchangeably in daily speech, they are not the same concept. When the printing house requests a “300 DPI image”, also clarify the actual size and resolution requirements it expects for the file.
Calculate pixels and centimeters together
To calculate, convert the physical measurement to inches: divide centimeters by 2.54. You can then find the PPI value by dividing the number of pixels in that direction by the measurement in inches. This calculation alone does not determine whether the detail is sufficient; The quality of the source image is also important.
For example, if a 3000 pixel wide image is used with a width of 25.4 cm, it will cover 10 inches of space. 3000 / 10 = 300 PPI. If the same image is expanded by 50.8 cm, it covers 20 inches and the density drops to 150 PPI. No new details occur here; the same pixels are distributed over a larger area.
Changing the resolution space is different from resampling
Changing the physical size to PPI relationship when resampling is off preserves the file's current pixel count. When resampling is on, the software can change the number of pixels. Added pixels do not mean that actual detail not present in the shot has been achieved.
After enlarging a small image, check especially the product edges, text and texture. If the source photo is blurry, a high PPI tag will not eliminate the blur. Adobe's description of resizing treats these two operations separately.
Do not impose a single value for each print
The catalog page and the large surface viewed remotely cannot be read under the same conditions. Printing method, viewing distance and manufacturer's technical conditions should be evaluated together. Saying "resolution is unimportant in big business" is as misleading as saying "everything must be 300".
With Selçuk Aker, the actual dimensions for which product photographs will be used can be determined early when planning a catalog or packaging design. Thus, insufficient source images are not noticed when preparing the final print file.
See pixel size for display
The area shown with CSS in the web image, device density and pixel size of the file are important. You cannot sharpen the web image by changing the PPI information alone. Also, prepare output with appropriate size and compression instead of uploading unnecessary large files.
Prepress preparation guide combines resolution control with other production conditions of the file.
Frequently asked questions
Can't a 72 PPI image be printed at all?
This label alone does not make the decision. Pixel size and actual print size should be calculated together.
Does the quality of the image increase when I set it to 300 PPI?
Available detail does not increase automatically. Resampling and source quality should be evaluated separately.
Does the same calculation apply to the vector logo?
Vector formats are not treated like pixel photos. However, embedded photos and some effects in the file may require resolution control.
