View Magnification in Photoshop
A few days ago I uploaded a video to my YouTube channel explaining PPI and DPI – you can see that HERE .
But there is way more to pixel per inch (PPI) resolution values than just the general coverage I gave it in that video.
And this post is about a major impact of PPI resolution that seems to have evaded the understanding and comprehension of perhaps 95% of Photoshop users – and Lightroom users too for that matter.
I am talking about image view magnification, and the connection this has to your monitor.
Let’s make a new document in Photoshop:
We’ll make the new document 5 inches by 4 inches, 300ppi:
I want you to do this yourself, then get a plastic ruler – not a steel tape like I’ve used…..
Make sure you are viewing the new image at 100% magnification, and that you can see your Photoshop rulers along the top and down the left side of the workspace – and right click on one of the rulers and make sure the units are INCHES.
Take your plastic ruler and place it along the upper edge of your lower monitor bezel – not quite like I’ve done in the crappy GoPro still below:
The minute you do this, you may well get very confused!
Now then, the length of your 5×4 image, in “plastic ruler inches” will vary depending on the size and pixel pitch of your monitor.
Doing this on a 13″ MacBook Pro Retina the 5″ edge is actually 6.875″ giving us a magnification factor of 1.375:1
On a 24″ 1920×1200 HP monitor the 5″ edge is pretty much 16″ long giving us a magnification factor of 3.2:1
And on a 27″ Eizo ColorEdge the 5″ side is 13.75″ or there abouts, giving a magnification factor of 2.75:1
The 24″ HP monitor has a long edge of not quite 20.5 inches containing 1920 pixels, giving it a pixel pitch of around 94ppi.
The 27″ Eizo has a long edge of 23.49 inches containing 2560 pixels, giving it a pixel pitch of 109ppi – this is why its magnification factor is less then the 24″ HP.
And the 13″ MacBook Pro Retina has a pixel pitch of 227ppi – hence the magnification factor is so low.
So WTF Gives with 1:1 or 100% View Magnification Andy?
Well, it’s simple.
The greatest majority of Ps users ‘think’ that a view magnification of 100% or 1:1 gives them a view of the image at full physical size, and some think it’s a full ppi resolution view, and they are looking at the image at 300ppi.
WRONG – on BOTH counts !!
A 100% or 1:1 view magnification gives you a view of your image using ONE MONITOR or display PIXEL to RENDER ONE IMAGE PIXEL In other words the image to display pixel ratio is now 1:1
So at a 100% or 1:1 view magnification you are viewing your image at exactly the same resolution as your monitor/display – which for the majority of desk top users means sub-100ppi.
Why do I say that? Because the majority of desk top machine users run a 24″, sub 100ppi monitor – Hell, this time last year even I did!
When I view a 300ppi image at 100% view magnification on my 27″ Eizo, I’m looking at it in a lowly resolution of 109ppi. With regard to its properties such as sharpness and inter-tonal detail, in essence, it looks only 1/3rd as good as it is in reality.
Hands up those who think this is a BAD THING.
Did you put your hand up? If you did, then see me after school….
It’s a good thing, because if I can process it to look good at 109ppi, then it will look even better at 300ppi.
This also means that if I deliberately sharpen certain areas (not the whole image!) of high frequency detail until they are visually right on the ragged edge of being over-sharp, then the minuscule halos I might have generated will actually be 3 times less obvious in reality.
Then when I print the image at 1440, 2880 or even 5760 DOTS per inch (that’s Epson stuff), that print is going to look so sharp it’ll make your eyeballs fall to bits.
And that dpi print resolution, coupled with sensible noise control at monitor ppi and 100% view magnification, is why noise doesn’t print to anywhere near the degree folk imagine it will.
This brings me to a point where I’d like to draw your attention to my latest YouTube video:
Did you like that – cheeky little trick isn’t it!
Anyway, back to the topic at hand.
If I process on a Retina display at over 200ppi resolution, I have a two-fold problem:
- 1. I don’t have as big a margin or ‘fudge factor’ to play with when it comes to things like sharpening.
- 2. Images actually look sharper than they are in reality – my 13″ MacBook Pro is horrible to process on, because of its excessive ppi and its small dimensions.
Seriously, if you are a stills photographer with a hankering for the latest 4 or 5k monitor, then grow up and learn to understand things for goodness sake!
Ultra-high resolution monitors are valid tools for video editors and, to a degree, stills photographers using large capacity medium format cameras. But for us mere mortals on 35mm format cameras, they can actually ‘get in the way’ when it comes to image evaluation and processing.
Working on a monitor will a ppi resolution between the mid 90’s and low 100’s at 100% view magnification, will always give you the most flexible and easy processing workflow.
Just remember, Photoshop linear physical dimensions always ‘appear’ to be larger than ‘real inches’ !
And remember, at 100% view magnification, 1 IMAGE pixel is displayed by 1 SCREEN pixel. At 50% view magnification 1 SCREEN pixel is actually displaying the dithered average of 2 IMAGE pixels. At 25% magnification each monitor pixel is displaying the average of 4 image pixels.
Anyway, that’s about it from me until the New Year folks, though I am the worlds biggest Grinch, so I might well do another video or two on YouTube over the ‘festive period’ so don’t forget to subscribe over there.
Thanks for reading, thanks for watching my videos, and Have a Good One!