[Guide] How to find the best available quality of images you want to upload to Furbooru?

This thread is meant to gather information about accessing best possible quality and resolution of images from various sites so that they can be uploaded to Furbooru.
 
Firstly, when possible always upload images from a file that is from the artist’s gallery. Note that sometimes artists upload their work on e621 or Derpibooru themselves and you might even find the best quality there instead of their other profiles.
 
If you stumble upon some low res image on the Internet it is always best to reverse search for the original submission.
 
You can do it using Google Images reverse search (https://www.google.com/imghp ):  
 
and if this didn’t help then you can try those:
 
https://saucenao.com/ - general art, including furry or MLP.
 
https://kheina.com/ - 40% of Fur Affinty and entire Furry Network indexed
 
https://derpibooru.org/search/reverse - for MLP themed images only
 
If you are using Telegram you can try this bot: @FindFurryPicBot
 
Secondly, fetch the image from a proper url. Exact way to do that is dependent on the site, details are explained below.
 
Generally it’s best to always use urls copied from download links and not from clicking on image itself, because images can be displayed only as a medium or low res preview instead of the original size.
 
Fur Affinity
 
Fur Affinity automatically resizes all images at first upload to be no more than 1280px in height or width. This can be circumvented by the uploader by using the “Change submission file” option, but most artist don’t do that. That means that when file on FA is only 1280 px there is a possibility that a larger version of that image exist on some other site where the artist posts their work, for example on Twitter or dA, it is worth checking there.
 
Nevertheless, to get the best possible resolution from FA right click on “Download” and copy that link to Furbooru url fetch.
 
 
Classic theme  
 
Modern theme
 
Copying image url from image itself instead of that Download link will result in a low res image if the image is not opened at full size. It’s best to always copy image url from Download link. Correct link will start with d.facdn.net
 
Twitter
 
Images from Twitter are fetched by Furbooru from the post url automatically in the best possible quality. Be wary not to fetch small images from direct urls because you might not get the best possible resolution or get a JPG file instead of PNG ones. Always use post url (starting with twitter.com/) and not direct links (starting with pbs.twimg.com/) for fetching.
 
If for some reason fetching from post url is not working and you have to do it from direct link then read this appendix to learn how to get the best file then.
 
Deviantart
 
Sometimes image fetched from post url can be of lower resolution then what can be downloaded. Sadly images from dA can’t be fetched from download link, they have to be downloaded and then uploaded to Furbooru as files.
 

 
If there is no download link, then, as explained in this Derpibooru thread:  

 
inkbunny
 
Copy link from “Download (new tab)” that is under the image to get the best possible resolution
 

 
Tumblr
 
Below is a quote from this thread on Derpibooru that explains how to get the best files:  

 
Furry Network  
“Download” link is on the right side, under the artist name
 

 
e621  
Always copy the url from “Download” button that is under the image:
 

 
Copying url from the picture itself might not provide the best possible resolution. When something like “Sample (800)” is displayed under the image then the image is lower than the original file available, don’t use those when uploading to Furbooru.
 
Derpiboru  
Copy url from one of those. Technically you can also use “View” or “VS” but with SVG files using them will give you a PNG file instead of the SVG one.
 

 
Copying url from the picture itself might not provide the best possible resolution.
 
————  
Updating/merging images on the site
 
If you want to replace an older low res/low quality image that is already present on Furbooru with it’s larger res/better quality version, upload the better version and then go to the worse image and report it for merging into the new, better one:
 

 
ID of the image is the value from image url that is after /images/

Appendix: Fetching from Twitter direct links if fetching from post url doesn’t work
 
I will use this image as an example: https://twitter.com/DreamWeaverPony/status/1218553001880801281
 
When opening this image in a new tab without enlarging the image first the direct url will be this:

 
Notice the format= and name= fields at the end of the url, they are important.
 
If you instead first clicked on the image to enlarge it and only then opened it via RMB -> open in a new tab you will get a bit different url:  

 
The name parameter changed from small to 4096x4096. If high resolution png is available then this will have “format=png” in the url, like it is the case on this post: https://twitter.com/bongwater777/status/1287573323052994564
 
You can check that if first enlarged and then opened in a new tab the format=png part is already in the url from the start.
 
I know of those available values for name= (but there might be more):  

 
Both 4096x4096 and orig will give the best possible resolution even when image is less than 4096px, this value seems to be Twitter upper resolution limit.
 
If you manually change the format= value from jpg to png even though you didn’t get a link with png from the start then although you will sometimes get a working image, that might not be a file of better quality!. Resulting file might be (or maybe even always is?) a PNG that has quality identical to JPG (with compression artifacts) but just have a higher file size. Do not upload such faux PNG files because they are not better than JPG versions then.  

 
Above is a such an image at 600% zoom. Part of url from first example was manually changed from containing_ format=__jpg__&name=4096x4096 (link) to format=__png__&name=4096x4096 (link), _the file size got over 4 times bigger, the format of downloaded file is PNG but image quality is identical to JPG, there are compression artifacts everywhere. There is no point in using images like that.
 
Note that changing format= to png will not work when name=orig but will work when name=4096x4096.