Controlling the image you have for a background in Flickr is a bit trick. I found it frustrating the last time I changed my background. I tried to sort it out again, as I wanted a new background. I did find a sizing that works.
The complication in sizing this image is from Flickr needing to resize the image on the fly to fit various screens. Below a certain size, they stop displaying the image. My Android Samsung S5 is an example (I don’t use the Flickr app) of where it isn’t displayed. However, they do display the image on my iPad.
Whether profile or landscape, the iPad uses a 1024 x 768 display of the web page. Flickr does not resize (respond to the change) as you change from profile to landscape. At least my old iPad doesn’t.
In Chrome on my desktop, you can see the background image changing size when the browser window resizes.
The yellow arrow shows the change where I think it is easiest to see. The image ratio has changed. It is because of this change that it makes it hard to figure out what image size to use.
The working size is 2048w by 768h. As best I can tell Flickr will show the 400 pixels denoted by the red area. This leaves 184px above and below the red that will be hidden, depending on the size of the browser window.
While I pointed to the 184px area at the bottom, you can see the top edge revealed more of the image too.
This image (above) shows how I would build an image to control what Flickr will show. (I didn’t do that for my current background on Flickr. 3/2017) The yellow strip area is where my image is too small. Flickr will stretch my image. I think Photoshop will do a better job of stretching than Flickr will. But, I haven’t tested that.
Once I have everything the way I want it, I would crop the image to 2048×768 and upload it.
Flickr Background Brightness
You are likely going to notice that Flickr shades the lower portion of your image with a transparent gradient. Notice the images I used above and compare it to the source image below.
You can probably see that the whole image has been darkened in the background display and the lower section heavily darkened. I take it that Flickr does this so their white text will be easily readable.
I think the darkening amount is calculated from the image. So, lightening the image to offset what Flickr does, doesn’t help. My testing is limited. But, I have tried to lighten images to offset what Flickr does. Not much joy.
The Profile Image
Sizing and controlling the profile image is easier.
Flickr gives us more tools to work with for this image.
I find it interesting that the 400 pixel height shows up again. You can use any size image as a source. The +/- slider allows one to scale the image up or down. Plus you can drag the image around.
The end result displayed on your Flickr page is 100px diameter. This editing panel allows you to work the image as a 400px diameter image. The final display will be a quarter the size seen while editing. Knowing this you can test an image to see how it will look down-sized.
Fortunately, Flickr doesn’t mess with anything other than the size of this image.
You can get a copy if my ‘sizing’ image from Flickr, just download it. Please like it, if you do.