I have an indirect solution for downloading images you find on iOS's default browser (or Chrome?), and it will require a PC. Images will be saved on PC storage at first. Then optionally copy them back to iOS with their original filenames and their folder structure. Would you accept this as a trade-off from ability to save images on iOS with original filenames to having images already backed up on your PC with original filenames?
Bookmark to download later (iOS)
If it seem obvious to you, then why aren't you gonna do it? I also haven't told you that they can be downloaded with automatic process in some form when you're on your PC. Read on.
I am using Safari's bookmark to remember images' urls and then when I'm on my PC, downloading the images from bookmark will be of little effort using a batch file. They will be downloaded on PC storage and ultimately have their filenames preserved. I will explain you how to copy and view them on iOS after I've given to you full prerequisites first.
Sometimes when there is an image that you would like to bookmark, that's almost impossible in iOS 8. That's why, I've made a necessary bookmarklet.
I've used three folders in my bookmark specifically for images I'd like to download off from website when I'm on iOS:
- Downloads - Not literally; for aria2c.
- Tabs Dump - So I can catch up later on iOS or PC.
- To PC Now - Similiar to "Tabs Dump", but especially when I'd like to download images at high frequency.
Actually, it's not only for images, but other files as well, if Safari can have their url (with file extension) in the address bar somehow.
View Bookmarks on desktop
On Windows PC, I use iCloud and iCloud bookmark for Firefox. It will sync bookmarks between Firefox and iOS, and thus PC can view images' urls I have bookmarked in Safari. I'm sure it can be done between Google Chrome browsers on both PC and iOS as well, but I haven't tried.
I use a batch file running with aria2c that can download images from urls in a text file.
An example of such setup for aria2c is:
- aria2c.exe (I suppose you have downloaded it)
- results.log (empty)
- urls.txt (empty)
All of these files are under \aria2c\ folder.
A batch file (download.bat) containing (personal information removed and replaced with [user]):
cd /d %~dp0
echo ^>^> aria2
echo Downloading . . .
aria2c.exe --async-dns=false --load-cookies="C:\Users\[user]\AppData\Roaming\Mozilla\Firefox\Profiles\[user]\cookies.sqlite" --max-concurrent-downloads=5 --auto-file-renaming=false --check-certificate=false -d "%~dp0..\Import" -i urls.txt > results.log
echo Download done.
--load-cookies= is optional; necessary for viewing images that require HTTP cookie. Remove it when you don't feel like it.
Just select all and copy images' urls from Firefox (or Chrome?) bookmark, paste them into urls.txt, and then let batch file do the job.
Review and organize
Review what it has downloaded in results.log whenever needed.
The only disadvantage with "bookmark to download later" is when an image has been removed from website (or url address has been changed?) before aria2c has a chance to download it, so be sure to use aria2c more frequently, or in case of url address changed, you can probably try to recall and revisit where you have bookmarked based on url (unlike local directories that every other images will have) with ERR and 0B/s you find within "Download Results" section in results.log.
Everything it has downloaded will be in \Import\ folder along with \aria2c\ folder. You can organize them through the use with batch file or organize them by yourself.
PC <-> iOS
To copy and view them on iOS, I recommend you have a file management tool for PC <-> iOS, such as iFunBox, 25PP (25PP for me personally), etc (possibly iTunes...?), and a file manager app for iOS such as Readdle's Documents 5.
I know it may sound bit complicated but I've gotten used to it. It will feel more convenient over time, at least it did for me.
So it's all point to PC, right? In the end, it's a fully functional computer that can do a lot more things, after all. iOS and Android are not. Use your iPad's bookmark to download something later when you don't feel like using your PC for a while.