I don't think you are going to like the real answer for this:
Every person with a Google sign-in is technically a Picasa user. All those Gmail accounts, Google+ accounts and so on have all been turned into users on all of Google's services.
What you probably really want to know is how many active users upload photos to Picasa? Even that is hard to measure, because active users of Google+ are actually storing their uploaded and share photos on Picasa (even if they don't ever actually go to the Picasa service).
We could tell you that Picasa has about 7 billion photos uploaded to it (more than Flickr, less than Photobucket, and a tiny fraction of Facebook). But it is unclear what the definition of a "user" is on Picasa, compared to normal photosharing services.
According to this article (http://thenextweb.com/mobile/2011/01/26/instagram-vs-picplz-which-one-should-you-use/) on The Next Web, PicPlz had over 200,000 downloads towards the end of January.
I would say because Picasa users (included me) were pationate about their pictures being stored in that nice piece of software. Tags, faces, coordinates and all meta data was there in ONE place!
Now suddenly all goes up to the Cloud and you do not have the same functionality there. Once google photos covers all Picasa functionality, THAT day I will like Google photos.
For me Google photos is kind of demonstration of google that they know “image recognition“ and can search within pictures but I am not intrested in that I want to use my own meta data. By image recognition I mean all those systemde
I would say because Picasa users (included me) were pationate about their pictures being stored in that nice piece of software. Tags, faces, coordinates and all meta data was there in ONE place!
Now suddenly all goes up to the Cloud and you do not have the same functionality there. Once google photos covers all Picasa functionality, THAT day I will like Google photos.
For me Google photos is kind of demonstration of google that they know “image recognition“ and can search within pictures but I am not intrested in that I want to use my own meta data. By image recognition I mean all those systemderived searches like “surfing” or “cakes” or “selfies”.
According to this Yahoo Flickr advertising pitch page there are currently 51 million registered Flickr members. http://advertising.yahoo.com/media-kit/flickr.html
Yahoo further cites "24.8 million unique U.S. visitors (nearly 80 million worldwide) spending an average of 2.7 minutes per vist to the site. Not all of these visitors would have accounts. Some can be just visiting the site, looking for stock photography, or just browsing. Yahoo doesn't disclose active accounts, but if I had to just make a wild guess I'd speculate somewhere between 10-20 million -- and I could totally be wrong o
According to this Yahoo Flickr advertising pitch page there are currently 51 million registered Flickr members. http://advertising.yahoo.com/media-kit/flickr.html
Yahoo further cites "24.8 million unique U.S. visitors (nearly 80 million worldwide) spending an average of 2.7 minutes per vist to the site. Not all of these visitors would have accounts. Some can be just visiting the site, looking for stock photography, or just browsing. Yahoo doesn't disclose active accounts, but if I had to just make a wild guess I'd speculate somewhere between 10-20 million -- and I could totally be wrong on that.
Both compete.com and comScore show that traffic has declined significantly in the past year at flickr.
Latest post by Paul Allen states Google+ is at 18 million (see https://plus.google.com/117388252776312694644/posts/CPvrWa4mmup) reported on by Mashable http://mashable.com/2011/07/20/google-plus-users/
The major difference is the intent of those who built the different services, intent which then diffuses in all the choices made in the actual act of building them.
The intent of Flickr was to allow pro & amateur photographers get visibility & feedback by a community of photographers. The intent of Picasa was to allow casual photographers to create galleries of personal pictures to share with select people.
Picasa “is a discontinued, cross-platform image organizer and image viewer for organizing and editing digital photos, integrated with a now defunct photo-sharing website, originally created by a company named Lifescape.”
On February 12, 2016, Google announced that the Picasa desktop application would be discontinued on March 15, 2016, followed by the closure of the Picasa Web Albums service on May 1, 2016. [24]
Google stated that the primary reason for retiring Picasa was that it wanted to focus its efforts "entirely on a single photos service" the cross-platform, web-based Google Photos. While
Picasa “is a discontinued, cross-platform image organizer and image viewer for organizing and editing digital photos, integrated with a now defunct photo-sharing website, originally created by a company named Lifescape.”
On February 12, 2016, Google announced that the Picasa desktop application would be discontinued on March 15, 2016, followed by the closure of the Picasa Web Albums service on May 1, 2016. [24]
Google stated that the primary reason for retiring Picasa was that it wanted to focus its efforts "entirely on a single photos service" the cross-platform, web-based Google Photos. While support for the desktop version of Picasa is ending, Google has stated that users who have downloaded the software, or who choose to download it prior to the March 15th deadline will still be able to use its functionality, albeit with no support from Google. [25]
Instagram is nowadays one of the biggest social media platforms around.
In September 2017, it was reported that Instagram had over 800 million monthly active users - that’s more than Europe’s population!
On top of that, it was reported that Instagram also had over 500 million daily active users. These are real people, logging into their Instagram accounts on a daily basis.
The influence Instagram has on our day-to-day lives is massive, and if we are to believe trends, this will only increase moving forward.
There is no single major difference between the two. They have a variety of differences, across multiple categories.
Business: One is owned by Google, the other by Yahoo!
Social: There are more social tools and better topical discussions on Flickr because it adds the layer of "Groups", which can have their own pools.
API: Flickr has been around longer and has more users, so more solutions using the Flickr API have been developed.
Client: Picasa has a desktop client for managing and editing photos
And so on...
Its certainly non-trivial
http://googlereader.blogspot.com/2010/09/welcome-and-look-back.html
Users vs. Time. Unfortunately there isn't a y-axis.
As of February 2014, "Flickr has grown to the point where it now has 92 million users, spread across 63 countries, who contribute to almost 2 million groups and share around 1 million photos every day." via Flickr At 10: 1M Photos Shared Per Day, 170% Increase Since Making 1TB Free
Probably Google will connect Picasa with Google+ in near future. They will drop the name, but make it better as a part of Google+. Now you have almost unlimited photo upload to Google+ Photos and it is really appreciated by photographers because Google+ doesn't change size of the photo.
I asked this question at the German Google Developer Day 2010 and a Google Engineer / PM who works on Buzz said it's "tens of millions active monthly users".
Picasa is now retired. (If you speak English, you can read the blog post here.)
After Picasa is retired:
•Picasa should continue to work anywhere it's installed, and you don't need to take any action.
•There won't be any more updates to Picasa.
•Picasa will no longer be available for download.
http://googlephotos.blogspot.com/2016/02/moving-on-from-picasa.html
(Pocket-lint) - Google-owned Picasa will be no more after this spring. The photo service was acquired by Google around 12 years ago and has long included native apps for Windows and Mac OS X as well as an integrated web app.
It was announced today that the Picasa desktop application will no longer be supported as of March 16, 2016.
Source: Google Is Finally Killing Picasa
92 million as of Feb 2014.
http://techcrunch.com/2014/02/10/flickr-at-10-1m-photos-shared-per-day-170-increase-since-making-1tb-free/
Google has never released that number.
There is an interesting infographic in which someone shows the scale of both various photoshare sites (all dwarfed by Facebook) and the number of photos every taken by mankind. You can see that here: http://blog.1000memories.com/94-number-of-photos-ever-taken-digital-and-analog-in-shoebox
Flicker's "Groups feature" is useful for sharing amongst interest groups.
Downloading multiple(or all) images is easier in picasa with one click.
I believe that google photos has superseded Picasa. Picassa stoped working for me some time ago so I went over to google photos and I have to say that now I prefer it as it has automated a lot of the functions like tagging and face recognition.
Internally, picasaweb, G+ Photos and Google Photos use the same backend so if you upload your photos/albums to picasaweb they will show up in G+ Photos and Google Photos.
The face tags will be uploaded and stored (and will show up picasaweb and G+ Photos). There is still some discussion around how face tagging will work in the new Google Photos app so I can't really say anything about what will happen with face tags.
I experience Google+ as the Social Network for business connections and rather an older target group than the youngsters. Especially because I use gmail for work I am connected with lots of business contacts on this platform. What is a great feature are the Google+ Ripples - it shows you everyone who has publicly re-shared your posts on the network and through a great visualization lets you detect key influencers of certain topics or industries. On top it gives you a few more statistical insights that can help you steer campaigns etc.
Picasa became Google Photos. Though I believe you can use the older versions of Picasa but do not expect any updates.
Google+ is also a social networking site. I personally use it only for work. I am using it for SEO and SMM.
Yes, there is little innovation over many years. But, Picasa is a great application to edit and view photos on any machine. Its free and fast. I don't think Google should change or drop this product. I have many friends who uses Picasa to edit pics for free.
Instagram has over 300 million active users as of December 2014.
It seems like that google will make a standalone service for the pictures. Currently everything is tied together, but they signaled that they might change it in the future. Until this is happening Picasa will remain on the market but will not be developed (Unless support for new OS), Hopefully a new google+ photos suite will follow. And don't forget. Google acquired Snapseed and NIK, they might even integrate it
not for linux
but ones a month they are updateing few bugs. No major changes since 2013!
1 million users was announced on Dec 21: http://bits.blogs.nytimes.com/2010/12/21/instagram-quickly-passes-1-million-users/
The latest figure is now 90 Million, with 54 daily active
http://thenextweb.com/google/2012/01/19/larry-page-google-now-has-90-million-users/