I want to call attention to a problem I see all the time when people source images.

If the source is from pixiv and the url you are using looks like this:
i.pximg.net/img-original/.../07/05/31/63015821_p0.png
then that will lead to a 403 error every time. The way to get this improper URL is to open an image from pixiv in a new tab. This shouldn't be done as pixiv provides the largest size without the need to do this. Usually if you went to this page from new tabbing the image on pixiv you would simply be able to click the image again and it would take you back to the regular image page but this does not work coming from external sites.

The way urls should look is this:
www.pixiv.net/member_illu...um&illust_id=63015821
With a full "pixiv.net" in the url. All you have to do to get this image is to copy the URL from the page the full size image is hosted on with the title and "add to bookmarks" options. The page you get to right after clicking on the image from the gallery.

There is also a similar problem in sourcing things from twitters and other sites. Generally you should never open the image in a new tab to copy the url from there as you will almost always not be able to go back to the artist's page. Basically making the "source" useless.

If the URL from twitter looks like this:
pbs.twimg.com/media/C3xtbuQVMAAJC6h.jpg:orig
Then don't even bother adding it since the only extra information you're giving is that it comes from twitter. A twitter url should look like:
twitter.com/hi_mekuriguri/status/827657133197889536
With a full "twitter.com" in the url. This links to the post and the person following the link can see the artist's page and open the image in new tab themselves if they need it in full size. By the way if you want an image from twitter to be in full size then open the image in a new tab and add :orig to the end of the url.

This goes for any site. Tumblr as well has this issue. It's impossible to find the source tumblr from only the image url due to their encryption. I hope at least a few people sourcing this way will change. I know not everyone is going to see this post. By the way if you want to find the actual source for a pixiv image after getting a 403 error, use saucenao to find it. I don't know why more people don't know about this. I see so many "artist request" images when all you need to do is use saucenao.

If the uploads you're seeing like this are from the danbooru importer, there's not much we can do about it, I don't think. I'm pretty sure we don't support uploading images via pixiv source links anymore, at least. Twitter twimg. links should still work, because that's a direct link to the image.

So the vast majority of Pixiv links that do that come in that way from Danbooru, due to the way they handle their source links.

Basically, if you're uploading from Danbooru, you just give Danbooru the link, they grab the image from the site themself, slap the direct image link in as the source, and credit you for the upload. The source link stays in that format and, if you access it through the API, that's how you'll get it. The reason that their post pages will instead have a link to the post page on Pixiv is that they have code that automatically converts it on the fly when rendering the page.

When we import posts from Danbooru, we just grab them off their API, so we only get the direct link. We used to have code that converted the source link on the fly, just like Danbooru, but they recently changed their address format for direct image links, and we haven't yet updated our code for it.

So, basically, direct Pixiv image links aren't something someone's going to get in trouble for. Just wait for our code to be updated to support the new format.

By the way, you can convert it yourself. Take the bolded bit here from any Pixiv direct link:
i.pximg.net/img-original/img/2017/05/22/07/05/31/63015821_p0.png

And replace the bolded bit here with it:
www.pixiv.net/member_illust.php?mode=medium&illust_id=63015821

You can even create a search bookmark that does this automatically for you. Create a bookmark that looks like this:
www.pixiv.net/member_illust.php?mode=medium&illust_id=%s

and give it a keyword, such as this:
pi

and you can type the following in your address bar to load the Pixiv post page for that number from the direct image link:
pi 63015821

This works in most browsers, even mobile ones, and can be done with all kinds of things on other sites too. I can load almost any page on Gelbooru directly using this; I can search the site using "gb <tags>", I can load a post by its ID by using "gbi <id>", I can look something up on the tag wiki by typing "gbw <name>", etc.

Also, you can just force your referrer to be www.pixiv.net when visiting the pximg.net domain, and you should be able to see any image even from a direct link.

I got an alarm message about posting artworks on Twitter from jedi, i should try and use Pixiv. But i know a lot of artists are using too much Twitter than Pixiv.

More of a courtesy message. If an artist posts only to Twitter then it's still okay.

Thank you very much. But some of my posts are gonna be deleted if the works are posted on Pixiv later.

Images get deleted if it is an inferior quality to another one that exists.