Sorting and culling large batches of images is Aperture's strong suit, thanks in part to its flexible viewing options and the Stacks feature. A Stack is a group of images that are automatically clustered, based on the elapsed time between shots. When the stack is open, Aperture arranges the images side by side but retains spacing between them so it's easy to navigate among the open stacks. This is an excellent solution for sorting through bracketed images or any time you have multiple shots of a subject. Furthermore, the ability to interactively determine the intervals for autostacking different shoots, previewing the results, is one of Aperture's coolest tools.
As its name implies, this tool provides an enlarged view of an image or a part of an image just by dragging it across the screen. You can magnify as much as 1,600 percent, and best of all, dragging the Loupe across a series of images will continuously display the closeup view of whatever image or section of image is targeted. There's no need to reset the tool or click the mouse, which makes it a really efficient method of examining images. Aperture supplies two types of Loupes: one that dynamically magnifies whatever is under your cursor, and one that provides a scalable zoomed view of the pixels under its center. The latter can also display the color values under the crosshairs in its middle.
Aperture employs floating, translucent panels called HUDs, or heads-up displays, which provide a convenient way to make various adjustments and, to some extent, allow you to customize the work space. The application offers a full set of tonal and color-correction tools, with the odd exception of curves. Though you can produce the same effects with histogram-based tools, curves make it much easier to spot when you've mistakenly created some bizarre contrast changes.
For editing, you'll find levels, white-balance adjustments, and a shadows-and-highlights filter, as well as cropping, red-eye removal, and more. Some, such as setting the white point, incorporate the Loupe, which makes it very easy to hone in on specific points in the image. Though you'll find several types of automatic adjustments, I find the automatic results from Adobe Lightroom far more usable.
Aperture's black-and-white conversion tools are a mite old-fashioned compared to Lightroom's; though the presets produce a fairly good initial result, you're then stuck tweaking it with the RBG mixer values that many users have trouble conceptualizing.
In Aperture, anything reconfigurable is considered "Smart." Query filters are Smart Settings. Referenced (as opposed to physically relocated) collections of photos are Smart Albums. Less smart is splitting the options for creating new albums, Web galleries, or slide shows into two separate choices: blank or populated by the currently selected photos. It simply clutters up the interface, just begging for you to click on the wrong one. Which I do, frequently.
Aperture's ranking system is fairly standard with its five-star setup, but it also has a hierarchical keyword system that's easy to use and makes retrieving images efficient. Multiple options are available for organizing images into various containers, such as projects and albums. The Light Table feature works well for experimenting with photo layouts, while the Web gallery publisher makes short work of creating a Web gallery.
The Web gallery publisher makes short work of creating a Web gallery, which offers a limited selection of templates but allows for interactive resizing of the grids. Aperture generates relatively clean code--it depends upon how strongly you feel using tables as a formatting tool. Though it doesn't supply a built-in FTP client, you can always find a third-party option, such as ApertureToFTP Pro. It lacks Lightroom's flashy Flash gallery options, though.
Aperture's print layout options may not be as glitzy or flexible as Lightroom's (did you ever think you'd hear that about Apple?), but it has one big advantage: it can automatically lay out and scale the images to obtain a specific page count.
Aperture's Spot and Patch tool works very similarly to Lightroom's Clone and Heal: you choose target and source areas, and can move either interactively while previewing the results. Each pair of areas remains editable, and you can add multiple pairs to an image. Aperture's Spot and Patch provides more flexibility than Lightroom's, however, allowing you to control the blending characteristics and rotate the source within the circle. This is exceptionally important for the kind of retouching I do--eradicating goop from the eyes of stray cats--where I get the best results when I can match the direction of the fur on the source and target areas.
Front and center is the Viewer, which displays images in any one of a number of variations: single, side by side, dynamically resized n-up, scalable thumbnails, and more. Two sidebars on either side contain a multitude of more collapsible panels and slide open or closed at the touch of a hot key. The Projects panel on the left provides quick access to the library and to various projects, albums, light tables, and so on. To the right, you can slide out Metadata or Adjustment Inspectors. There are plenty of keyboard shortcuts for the program, with alternate access via the toolbar and the control bar.