Can I use a batchfile to read the size of an online picture and write that size to a file?

Nope.

There are lots of things you can't do in a batch file, and this is one of them.

Why?

1) BATCH predates the internet, buy a couple decades. So there was never any built in support for getting stuff from the internet, and there never will be.

2) The link to the image won't tell you what the width or height of the .png file is. About all you can do with the link is download the file. Until the file is downloaded, there is no way to figure out the width and height.

3) You *could* call wget or curl from a batch file to download the file. That gets you part way there...you at least have the file. But BATCH doesn't have any built in support for reading a binary file like a .png to read the width and height attributes.

Trying to do this from a batch file will be an exercise in frustration. You are better off using a more modern scripting language, or a real programming language. You can probably do this in a .VBS file, not sure, didn't try it, but I suspect you can.

You can also do it using PowerShell. I'm not all that handy with PowerShell, but I managed to put this together in about 10 minutes, and it does what you asked for:

add-type -AssemblyName System.Drawing

$webclient = New-Object System.Net.WebClient

$url = "https://www.google.com/images/srpr/logo4w.png%22

$file = "logo4w.png"

$webclient.DownloadFile($url,$file)

$png = New-Object System.Drawing.Bitmap $file

Add-Content width.txt $png.Height

Add-Content height.txt $png.Width

You can BUT you need a third party command line jpeg utility ....then its:

3rparty.exe myimage.jpg >> outfile.txt

Check out this discussion at the link below -- especially where they discuss "imagemajick" --