You may have noticed small pixels on your LCD screen do not change colour when flicking through images. Hopefully, this is a temporary issue rather than a permanent one.
Dealing with stuck vs dead pixels can be a hassle. But with our guide, you can find out what type of issue you are facing. And what to do about it.
What Is a Megapixel?
A digital camera captures images through what we know as pixel elements. Better known as pixels. This means a megapixel is one million (1,048,576 pixels) of these pixels.
A camera sensor, like the Canon 5D Mark IV, can have a resolution from anywhere between 12 and 60 megapixels. A resolution of 30.4 Megapixels equals 31876710.
Digital images come from thousands of tiny tiles capturing light and colour. The more pixels, the better the photo resolution.
Its funny, that out of these millions of tiny dots, we can tell when one isn’t working as it should.
It’s like the Princess and the Pea, except it’s the photographer and the petulant pixel.
Stuck Vs Dead Pixel
A pixel acting up is a hardware problem, They are not supposed to become stuck or cross over to the dark side. This is caused by manufacturing flaws. You see, pixels aren’t supposed to stick or die over time.
Stuck and dead pixels are different. A stuck pixel retains some colour, staying either red, green or blue.
A dead pixel is black. It is very possible to unstick a stuck pixel, yet the same doesn’t go for the dead pixels.
On the flip side, if you have a pixel that only displays white, that is a hot pixel. These come about when camera sensors are used for extended periods of time.
Don’t worry, they disappear.
How to Check Stuck Vs Dead Pixels
Your LCD camera screen is the place where your digital images pop up. Here, you see the photodiode information as a visual representation, thanks to the cameras’ processing algorithm.
Sometimes you don’t need to search for these pixels, as fixing them can be very easy. Some cameras have a noise reduction feature that removes hot pixels from your final image.
This involves photographing with the lens cap on, so the sensor can see where the problem lies.
These are great, yet they don’t help in checking or fixing stuck pixels.
Don’t panic just yet. What you may think is a stuck pixel may just be dust stopping the diodes doing their job.
Clean your DSLR sensor first to eliminate that as a possibility.
How to Fix Stuck Vs Dead Pixels
There are a few ways you can try to fix the stuck pixel, and they range from free and easy to expensive and complicated.
Have a look at what options are available, and go from there.
Some camera manufacturers have in-camera stuck pixel fixing features. This will depend on the camera make and model. A little research can go a long way.
Remapping – The official solution offered by camera manufacturers is ‘remapping’. This locates the stuck or dead pixel and tells the pixel to take information from the surrounding pixels. If your camera is not under warranty, expect to pay up to $200 for this fix.
Some camera manufacturers, such as Olympus, include pixel remapping features in their firmware. By activating the pixel mapping option, and capturing a black reference frame you can sort this problem out.
Shaking – Many camera models on the market today have an auto cleaning feature. A tiny motor inside the CMOS sensor vibrates to an ultrasonic frequency, shaking off dust.
This is a free option, so start with this if you have it available. Some camera manufacturers, such as Canon, pair the cleaning function with a remapping feature, they just don’t tell you about it.
One of the reasons stuck or dead pixels look so big on a jpg is down to the in-camera processing. The easiest way to remove the bloom around the problematic pixel is to photograph in RAW.
When it comes to retrieving that jpg, just run the RAW image through a RAW processing tool. Adobe Camera RAW or Lightroom. These tools interact with the RAW format in mapping out the troublesome pixels.
If you don’t have or need the bigger RAW software packages, you can use the free application for Windows. It is called Pixel Fixer, and you can find it here. This is a great tip on how to fix a dead pixel.
Edit Images (Manual and Batch)
If you don’t want to shoot in RAW, or found the problem after capturing the image, this option is for you. Here, you can manually edit the images yourself.
If you are using a decent editing software, such as Photoshop, you can edit out the problematic pixels. Simply record your ‘spot healing’ actions and semi-automate the process across all of your images.
Obviously, this technique will only work with images taken with the same camera. Also, you need to consider the original resolution and cropping, as this process remembers the exact locations of the pixels.
Create and Examine a Reference Photo
Grab your camera and switch it to manual mode. Set it to a high ISO, such as 800 or above, and the shutter speed above 1/1000th of a second. The aperture doesn’t matter.
Put the cap on the lens, and snap a few shots with your thumb over the viewfinder. This is creating the reference photo.
Load the image into Photoshop or GIMP. The idea here is to spot and then blend these stuck or dead pixels using actions. Scour the image for anything that isn’t pure black.
Create and Test an Action Set
Now we have a reference photo, we can create an action set. This records the actions for removing the stuck pixels. You can do this manually, but it’s easier to do it automatically.
In Photoshop, open the image. Zoom into the stuck pixels and select the Spot Healing Brush by pressing “J” or selecting it in the toolbar. Adjust the brush size so it only covers the pixel.
Try the brush to see if it removes the colour and returns it to pure black. The goal is to use the healing brush as little as possible, as your images won’t have a pure black background.
After you have tested the brush, and are happy with the results – undo them (Edit>Undo or CTRL + Z). We will start with a fresh image.
Open the actions window and click on the ‘New Action’ button on the Action window’s toolbar. Name your action specifically, such as ‘Stuck Pixel Fix – Canon 5D Mark III’. This ensures you don’t mix them up.
For this to work, you need to make one, small tweak. Click-on the fly-out menu in the Actions window and ensure the “Allow Tool Recording” is checked. If you don’t, the Action process will not pick up the tools you use.
With the action named corrected, and the tool recording checked we can start. Click the record button (red circle) at the bottom of the Actions window. From this point on, everything you do will be recorded.
Now we have our Action set, it’s time to test it. With a new image loaded, and your action set selected, press the ‘play’ icon on the Action toolbar to run the action set.
Watch the pestilent pixels vanish before your very eyes. Look around the image for any other problematic pixels. If you find any, you can add extra actions to an existing action set.
Select the Spot Healing Brush and press the record button. Touch up any other stuck pixels and then stop recording when you are finished.
A note from Josh, ExpertPhotography's Photographer-In-Chief:
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