Learn how to adjust the size of your image to print. Page size and margins.
It is important to set the image size for the paper size you want to print. This document will show the parameters to change in Photoshop and the effect on printing.
Let’s start by saying that you should keep the resolution of your file. The image size dialogue is risky as it can delete pixels from your image.
What is "dpi"? Does it need it to be 300 dpi?
DPI stands for dots per inch, which represents the amount of color or grayscale dots contained in every square inch. The higher the DPI, the better the print quality is expected, as the printer receives more information and detail to work with. However, the maximum output is restricted to the printer resolution. Typically, printers perform their best when they obtain a file with a DPI of 300 or more.
A4 @ 300 dpi
A3 @ 212.15 dpi
If we want to print a photo on an A4 size @ 300dpi you will need a file with and an A3 size also @ 300dpi, we would need a file of size 24.9M as 2480 px X 3508 px.
The same file (2480 x 3508), when printed on an A3 paper, would have 212.15 DPI. So, DPI is relevant to the size of the file you want to print. As you can see, the same photo will have less “quality” when printed larger.
The image size dialogue in Photoshop
This photo from inside St Francis catholic church in Melbourne Australia has the size of 8544 px X 5051 px. If I want to print it with a size of 28 cm wide, it will be 16.55 cm high.
The file to be printed at that size has 775.063 dpi. That is a number quite more than our “best” famous 300dpi.
Note that the Resample tick box is NOT ticked. This is SUPER IMPORTANT.
If you tick this box and change the size of your image, you will delete pixels or artificially add pixels to your image.
Note that the image size and dimensions remain the same when you change the image size.
What would be the max recommended size you can print? (Print at 300dpi)
As most printers will produce an excellent result when printed at 300 dpi, just change the resolution to 300 dpi and see the max recommended size to print. In this case, a 72 cm x 42 cm print is the maximum recommended print size.
What would be the max size the print will still look good? How much bigger can I go?
You can normally get a good print at 170 dpi, so if you want to have a larger print without the artificial creation of pixels, change the resolution to 170. In this case, you can get a 1.2-meter long print.
There is nothing that guarantees that a print with 170 dpi will look good and will have no issues on all printers. In most cases, based on my experience (paper + sharpness + distance of view + printer types), a print with 170 dpi is normally quite good.
Note that there is special software that manipulates the image to produce files that print well on super large sizes, or when the original file is of very low resolution for the desired print size. These programs analyze the image and create extra pixels based on other pixels. If you need any of this, please contact me.
Why it is a good practice to adjust your print size before sending the file to a printing company?
The solution is to inform the printer about the size of the desired image.
Suppose you want to print on A3 paper. It doesn’t necessarily mean you want to cover the entire sheet. The image’s aspect ratio may differ from that of the A3 paper aspect ratio.
In this example, I intend to print the church with a length of 28 cm on the longer side, leaving a large portion of the A3 paper white.
Note the image was scaled to 100% which means that it will be printed with the size specified on the image size dialogue and centered on the paper.
As the paper in this sample is an A3, we have a significant margin.
You can adjust the position of the image inside the paper as well.
What if I want to use as much of the paper as possible?
There are two options. The first one is to change the size of the image on the image size dialogue to the size of the paper – margins.
The second option is to click the “scale to fit media”.
I have never noticed any difference between the options.
The image now goes almost to the edge of the paper. It also has top and bottom margins as the image aspect ratio is not the same as the paper aspect ratio.
These small margins represented in this image as areas with diagonal lines are defined by the printer’s manufacturer. They are useful when placing the image in frames and mats. It is good to have an area to glue.
Borderless print
Some printers can print edge-to-edge and the results are often very good despite this warning.
In our example, as the aspect ratio of the photo is not the same as the paper, we will still have the top and bottom margins.
So, my suggestions are:
- Decide on the size you want to print after inspecting the image size window. Change the width and height and notice the resolution. Attention, do not tick the resample
- Consider that the image needs to fit on the paper. For example, the A3 paper size is 297 x 420 mm.
- Decide how much margin you want to have or if you want to crop the image to achieve the paper aspect ratio.
- Always set the image size to your printing size and save the file to be sent to the printer.
If you want to print significantly smaller than the paper size, you will have margins and you can decide the size of each one. You can have the image sitting lower or higher on the page. It does not need to be always in the middle.
Please contact me if you need any printing or read about our printing on fine art paper here. Thank you.
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