Do you print your images?
You should. It’s awesome!
There is something really special about holding one of your own images. Apart from completing the actual photographic process and ending up with a tangible product printing your images will add a whole new dimension to your photography. Another (real) goal to shoot for.
One of the things that a lot of people struggle with is the sizing of a print and what size a digital image needs to be in order for it to print at an acceptable resolution. This is a question I got asked a week or so ago and I know many people have struggled to get their head around this so let’s try and break it down.
Before we dig into some of the details around resolution and how cropping affects it check out this video in which I run you through the basics.
The resolution of an image refers to the amount of pixels in that image.
For example, an image sized to 4,928 x 3,264 pixels will have a resolution of 16,084,992 pixels.
Yeah, that’s 16 million pixels or like we all refer to it, 16 megapixels.
You can try it at home. Just take the dimensions of your image, multiply them with each other and there you have it.
You can find the dimensions of your image quite easily in Lightroom.
Check out the video to see how easy it is.
Cropping Affects Resolution
If you are not going to crop your images it’s going to be pretty easy to calculate the actual print sizes you will be able to print. If you know your camera shoots, for example, 21 megapixels you can just calculate your maximum print size once off but, and it’s a very important but, cropping will influence the resolution of your image and subsequent maximum print size.
In the same way as we calculated the megapixels of the image above, watch what happens when I crop it in a little and then recalculate the megapixels of the images.
The new, cropped dimensions of the image is now 3,906 by 2,586 pixels which means the new size of the image is 10,100,916 pixels or 10,1 megapixels. That’s a 6 megapixel, or 6 million pixels, reduction in resolution.
Or think about it this way.
By cropping the image I have reduced the amount of pixels – information in the frame – by around 30%. It should start making sense that the less information you have to work with in your images the smaller the prints you will be able to produce.
Calculating Print Size
So now that you know how to calculate the resolution of an image, let’s see what size we will be able to print it in a very plain and simple manner.
It’s a generally excepted guideline that the resolution for print images should be 300dpi, or dots per inch, which then refers to the amount of information per square inch of the final print. Let me know if you would like to delve into this in more details and we can look at it in another post but for now let’s keep it basic.
So, if we are not sitting with an image like the cropped one above – sized at 3,906 by 2,586 pixels – we simply divide each of the side by 300 to determine the final print size in inches.
Pixels / required resolution = final size in inches
3,906 pixels / 300 dpi = 13.02 inches
2,586 pixels / 300 dpi = 8.62 inches
Therefore, if I wanted to print my image above at a resolution of 300dpi I would be looking at a print size of around 13 x 8.5 inches.
To get my print size in centimeters I would just multiply these measurements by 2.54 – standard conversion from inches to cm – giving me a print size of 33 x 22cm.
Some of the common print sizes in inches include:
- 4 x 6
- 5 x 7
- 8 x1 0
- 11 x 13
- 16 x 20
Can you see that by cropping you are not only reducing the amount of information in your images but you are also limiting the maximum size to which you can print your images? Also, remember that there are ways in which you can upsize your images and other factors like acceptable viewing distance also plays a role in this but if you use the above as a guideline you should get decent results when you head out to print your images.
Hope that helps a bit but feel free to shout if you guys have any questions!
Until next time.
Gerry van der Walt
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