So, last month, the photo giant introduced Photoshop Express, its free Web-based service for storing, sharing and editing photos, in an effort to compete with established online photo services such as Yahoo’s (YHOO) Flickr, Google’s (GOOG) Picasa Web Albums, or the photo-laden Facebook social-networking service.

Photoshop Express has many of the same features as Flickr and its ilk. It gives you two free gigabytes of photo storage. But Adobe is hoping to make its mark with editing.

Most online photo services offer little or no editing, assuming you’ll do that using software on your computer before you upload your pictures. But Photoshop Express, borrowing from Adobe’s deep knowledge of photo editing, offers the nicest set of Web-based editing tools I have seen. They are sophisticated for a consumer application, yet easy to use. They edge out those in Picnik, a pioneering Web-based photo editor I hailed last year.

These slick editing tools are not only available for use with photos you’ve uploaded from your hard disk. You can also use them to edit pictures stored in your accounts at Facebook, Picasa Web Albums and another big photo-storage service, Photobucket — all without leaving Photoshop Express. You can even move pictures between Photoshop Express and these three services just by dragging and dropping.

Adobe’s new service is available in the U.S. only, at www.photoshop.com/express.

I’ve been testing Photoshop Express and its service overall is pretty good, even though it’s still labeled “beta.” It’s a nice example of the Web 2.0 trend, where programs accessed via a browser can look and feel like applications that live on your computer.

But Photoshop Express is rough around the edges. It can be slow at times, and it’s missing some obvious features, like the ability to easily download publicly shared pictures from other members or to print photos. Adobe says it is working on these things.

Photoshop Express isn’t meant to replicate all the features and power of Photoshop. It’s more like a Web-based version of Photoshop Elements, Adobe’s consumer software package.

I tested Photoshop Express on multiple computers: PCs running Microsoft’s (MSFT) Windows XP and Windows Vista, and Macs running Apple’s (AAPL) Leopard operating system. I used it in all three major Web browsers: Internet Explorer for Windows, Firefox on both Windows and Mac, and Safari, also on both platforms. It worked fine in all of these operating systems and browsers, though it does require Adobe’s free Flash software.

For my tests, I uploaded from my computers dozens of photos, from very large images captured with good digital cameras to smaller shots from cellphones. All were handled perfectly by Photoshop Express. I also opened and edited pictures in Photoshop Express from my accounts on Picasa Web Albums and Facebook. All of this worked well, though uploads of large images can be slow if your Web connection is pokey.

Photoshop Express is a handsome product, presenting your photos on a gray background with controls and features arrayed at the top and bottom, and down the sides, in a logical, clear manner. Your own photos are presented in a section called “My Photos,” and can be organized into albums. Photos that other Photoshop Express users have chosen to publicly share are organized into collections called “Galleries,” which can include multiple albums. You access these community photos by simply clicking on “Browse” or performing a search.

For each album you create, you can choose to share it publicly or to keep it private. Whichever option you choose, you can email friends either a link for viewing the album or a single photo. Your own photos can be downloaded at a variety of resolutions, including original size.

When you view shared galleries or albums, they appear as slide shows. You can select a number of slick effects by which the slides appear, allowing them to zoom and glide into place from various directions.

The editing features really stand out. In addition to standard tools such as auto-correction and red-eye elimination, Photoshop Express lets you touch up areas; adjust exposure, saturation, and lighting; and even make certain colors pop — so grass is greener, for instance. And, in most cases, it shows you small example images illustrating the changes, then previews those changes in the larger main image just by moving your mouse over the example. You can revert to your original at any time.

Unfortunately, there are a number of problems. Photos, especially large ones, can take awhile to appear in the editing module and to snap into focus. Captions sometimes get lost or mixed up when you move photos to other services. You can view shared albums only as slide shows, not as individual photos.

Still, Adobe has made a good start with Photoshop Express, and it’s worth a try if you want better online editing for your pictures.

Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

Such Web-based software has existed for years, but it was clumsy, slow and simplistic — no match for locally installed software. Common techniques, such as dragging items around the screen, were impossible. Seeing the results of an action often required the Web page to reload.

Now, developers are churning out Web-based applications that are so fast, rich and smooth they can hardly be distinguished from standard programs. And because they live online, these Web applications can be constantly updated; can run on both Windows and Mac computers; and can be easily integrated with other Web sites and services.

One of the best examples of these slick new Web-based application is Picnik, a sophisticated, photo-editing application offered free of charge at picnik.com. I have been testing Picnik and I like it a lot. It’s a fast and impressive program for tweaking and improving your photos, then posting them to popular photo Web sites, saving them to your own computer, emailing them, or even printing them.

Picnik, which comes from a small Seattle company called Bitnik, isn’t meant to compete with Adobe Photoshop, or to serve professional photographers or dedicated hobbyists. Instead, it’s for the same casual photographer who would use the limited editing tools in Apple’s iPhoto or Microsoft’s Windows Vista Photo Gallery.

Picnik isn’t a place to store your pictures, or a way to organize them — yet. The company says it will consider adding these features down the road. For now, it is focused on being an editing complement to popular Web services — such as Yahoo’s Flickr, Google’s Picasa Web Albums, and the independent Facebook — that already allow for storing and organizing photos. You could also easily use it as the main editor for photos you store on your hard disk.

The program is currently in beta, or test, phase, though in my tests it worked smoothly and surely. During this beta period, all of its features are offered for free. Later this summer, the company expects to end the beta period and begin charging something like $20 or $25 a year for access to some of the more rarified special effects that Picnik offers, though the core editing and sharing functions, and some of the effects, will remain free.

In my view, Picnik has a beautiful and responsive user interface that worked perfectly on the multiple Windows and Macintosh computers I used to test it. It worked equally well in the latest versions of the three best-known Web browsers: Microsoft’s Windows-only Internet Explorer, Mozilla’s Firefox (on both Windows and Mac) and Apple’s Safari (on both Mac and Windows.)

Picnik uses a simple tabbed interface across the top to navigate among its major functions. Edits and changes are previewed in real time, instantly, without the need for a page refresh or reload. Actions are confirmed with translucent messages that pop up on the screen and fade gracefully.

Any edit or special effect can be undone or redone instantly, all the way back to the original version of the picture, which Picnik retains on its servers during the editing process.

For example, you can zoom in or zoom out on a picture with a slider that works just as it would in a local program — the effect is immediate, with no jerkiness. If you wish to crop a picture, a pane representing the region to be included in the crop is superimposed on the photo. Everything inside the pane is sharp and clear, and everything else is faded a bit. This pane can be dragged, or resized, in real time.

Another example: If you want to tint a picture, the program shows you a color palette with a white dot you can move around the palette to pick your tint. As you do this, or move a slider that controls the intensity of the tint, the changes are instantly previewed in the picture.

None of this is unusual for a standard photo program installed on your computer, but it is impressive to see these effects happen so quickly and interactively in a program functioning over an Internet connection.

Picnik’s makers have struck partnerships with Flickr, Picasa and Facebook, and you can easily fetch pictures from these sites and post new pictures or edited versions of the originals back to the sites. You don’t need to switch to the sites themselves, they appear inside the Picnik Web page.

You can also upload pictures for editing from any other Web site, or from your hard disk, and you can email pictures to friends or to a wide variety of other sites, such as PhotoBucket, SmugMug and Snapfish.

The designers of Picnik have done such an elegant job that I wish the site would allow storage of photos, or organization of photos across your multiple online accounts and your hard disk. If you want to see how good a Web application can be, take Picnik for a spin.

• Email me at mossberg@wsj.com. Find all my columns and videos online free at the new All Things Digital Web site, http://walt.allthingsd.com.