Youtube has two main areas where you can add photos to your Youtube channel. One is your profile image, which is used across Google properties, from Gmail profiles to Google+ pages. You set that within your attached Google+ profile (and if you try to edit it within YouTube you'll be directed over to your Google+ profile).
The other is what Youtube calls "Channel Art," which is basically the same thing as what other social media services like Facebook, Twitter, and Google+ call the cover photo. On a regular website, it could be called the hero image. It's also often called the Youtube banner.
In 2017, Google gave Youtube a facelift, tweaking things like the logo and layout. It also included some relatively minor tweaks to the channel art feature.
You can, of course, watch Youtube on all sorts of different devices, not just on desktop computers. And how the channel art (or banner) displays is going to change according to the device. On a desktop web browser and on a mobile device it shows as a narrow horizontal panorama with an aspect ratio of 6.2:1. If you're using a TV, it's a full-screen background image in an aspect ratio of 16:9. But you can only specify one image to be used, so you need to make sure it's one that works in both the horizontal strip (or panorama) format as well a more conventional full-screen aspect ratio.
Youtube Banner Size Recommendations: Minimum, Maximum, and Recommended
Before we get to how to change and customize the channel art for your Youtube channel, you'll need to make sure you're using an image that meets the basic size requirements for the Youtube banner.
Youtube Banner Minimum Image Size
It has to be at least 2048 by 1152 pixels. If you try to upload an image smaller than that you'll get an error message that looks like this:
If you try to use an image that's already uploaded to the Your Photos tab, you'll notice that any that are too small are grayed out, and you can't select them.
Youtube Banner Maximum Image Size
The maximum size isn't limited by dimensions, but it is limited by file size to 6MB.
Recommended Image Size for Youtube Banner
The size that Youtube recommends you use is 2560 x 1440 pixels.
How to Add Youtube Channel Art
If you're just starting up your Youtube channel, the channel art space is blank by default, so you'll need to add some to get things started. If you already have existing channel art, the method for changing the image is essentially the same.
This is something you can do either in a web browser or the mobile app. Since there are some differences, albeit minor, between them, I'll walk through each separately.
Changing Youtube Channel Art in a Web Browser
When you go to your channel page (click on the profile image at top right and then choose My Channel) you'll have two buttons: Customize Channel and Creator Studio. (This is slightly different if you're replacing existing channel art--click on the small pencil icon at the top right of the image instead.)
Click on Customize Channel. You'll be taken to a layout guide that includes small mockups of how it will look on a desktop browser, on a TV, and on a mobile device. If you haven't uploaded any channel art previously, you'll just see a gray box placeholder.
Click on the Add Channel Art button.
In this example, I'm going to upload a new photo to use. You can also choose existing photos using the Your Photos, which includes photos and images you've uploaded to your Google+ account, and Gallery (free photos) tabs. But to upload a new one, click on the Upload Photos tab and either drag and drop an image onto the panel or hit the blue button that says "Select a photo from your computer."
Once you click on that, you'll have a familiar popup where you can choose which photo to add. By default, it opens to the Upload Photos tab, which is pretty self-explanatory.
Once you've selected the image, you'll get a preview of how it looks on desktop browsers, TVs, and mobile devices.
If it looks good to you as is, go ahead and hit the Select button.
Adjusting the Crop of the Youtube Banner
By default, the viewport is centered. So the panoramic crops will show the full-width of the image through a narrow part of the middle. You can, however, adjust the crop to move it to a different part of the image. Just hit the Adjust the Crop button at the bottom left.
The crop screen works a bit unusually in that it includes two areas. The clearest section, in the middle, is the horizontal panorama area that will be used on desktop and mobile devices. The larger area with the grab handles is the area used on Youtube-enabled TVs.
You can only adjust the larger crop--the narrow area will move along proportionally with it. Unfortunately, there's no way to shift the panorama section relative to the larger TV crop--it's always in the middle. So if you want to use something like a logo or text, you'll want to make sure it's safely within that inner area.
How much wiggle room you have vertically will be based on the aspect ratio of the image you uploaded. If you uploaded a 16:9 image, you won't have much room to move at full-width. But what you can do is reduce the width as well to focus in on a smaller part of the image.
To move the crop, you just click and drag. If you want to resize it, use the white square handles on the corners.
Once you've selected the focus area, click on the Devices Preview button at the bottom left to see how the changes will look.
You can also use the Auto Enhance button at the bottom right to help improve the image. How much effect it has--if any--depends on the individual image.
Once you're happy with the selection, hit the Select button. You'll then go back to your regular Channel view, and you're new Channel Art will be displayed at the top.
Changing Existing Channel Art
If you decide you want to change existing channel art, log into you Youtube and go to your channel's home page. Then move the mouse over the cover art. A small edit button will appear over the top right corner of the channel art. Once you click on that, you'll get a popup menu that includes Change Channel Art.
Adding Youtube Channel Art in the Youtube Mobile App
You can also add and change the channel art using the mobile app. It's fundamentally the same process, although it looks different enough that I'll include a quick walk-thru of it here.
You want to go to Home in both the top menu and the bottom one. Then click on the small gear icon.
In the Channel Settings screen, click on the camera icon at right. (The one in the middle is to change your profile picture.)
You'll then get the option to choose from the photos that are on your phone or tablet.
You'll then automatically be shot the crop preview screen where you can see which part of the image will be the basis for the viewport for the desktop browser and mobile views. You don't get a separate preview of the full-screen TV view this time.
Once you're happy with how it looks, tap on Use Photo.
Adding Logos and Text
You can add logos and text to your channel art before you upload it, but you're going to have a very narrow band to work with. And because of the way in which Youtube's crop tool works, precisely where on the original image it should be placed will depend on the aspect ratio of the original image. So unfortunately in many cases, it's a matter of trial and error.
But if you happen to be using an original image that is 2560 x 1440 pixels, there's a safe-zone rectangle precisely in the center that's 1540 x 427 pixels.
It will display like this:
In practice, you end up with something like this:
You can, of course, put the logo over an image. I've just used a plain white background here to make it clearer for illustration purposes.