Google only allows image search from the camera directly (and not the gallery), but doesn't allow iPad users to search by uploading an existing image or typing a specific URL.
How can I search by image from an iPad?
When you're on the Google Images page scroll all the way to the bottom. There is a choice there to use either Google Tablet or Classic (defaults to tablet on the iPad). Click on classic and you should get the same options as on your mac/pc.
If you don't mind installing and using Google Chrome browser, you can tap-hold on any image and the "search google for this image" link is right there. Imho the easiest option.
Here is an app-free way to perform Google Image search on Safari (ios devices)
Tap and hold on the picture you want to search and choose Copy to take its link.
Go to google.com, choose tab Image and paste the link into the search box and enter.
You will see the text For matching images, try search by image right under the menu bar . Tap on "search by image" and here we go!
Hope this help!
Reverse image search is especially helpful for determining the original author of the image and, for the photographer, seeing if any of his or her photos were used without permission. For mobile and desktop you can use https://searchbyimages.com
Use the Google Chrome app for iOS.
Hope this helps! This does NOT work in Safari.
You can obviously also do typed words.
Use an alternate browser like Opera, go to the settings, delete the cookies and change the User Agent as "Desktop" instead of Mobile, then open images.google.com. You'll have the camera icon like on your desktop browser.
I would recommend http://searchbyimages.com is a reverse image search engine. Search by image: Give it an image and it will tell you where the image appears on the web.
Download the app Puffin Free and go to Google.ca, then go to images. The camera should be beside the microphone.
You could use "Image Web Search" from the App Store. Here's a link to it.