Photoshop Vs. Picasaby Darrin Koltow
Learning about the differences between Photoshop and Picasa helps you decide on which program is best for your image-editing needs. Note that Photoshop is not just image-editing software, but a full-fledged painting program. Picasa has no painting functions, so it's only fair to compare the two programs as image editors.
Cropping in Photoshop involves using the mouse to define your own cropping region, while in Picasa you can quickly crop a picture to a frame that the program suggests. To crop in Photoshop, click the tool palette icon shaped like overlapping right angles, drag in the window to define your cropping region, then press "Enter" to crop the image to the defined region. To crop in Picasa, choose from a list of preset dimensions for your picture by clicking the dropdown list in the "Crop photo" pane. Picasa will offer three suggestions for cropping the picture to the dimensions you selected. If you don't like any of these, drag in the window to define the region you want to select. Picasa will constrain your selection to the dimensions you chose.
Rotating pictures precisely in Photoshop involves working with a box surrounding the image you want to rotate, while in Picasa you adjust rotation with a slider control. To rotate a picture in Photoshop by 90 degree increments, click the "Edit" menu's "Transform" sub-menu, then click one of the "rotate" items, such as "rotate 180." For rotations of an arbitrary degree, press "Control" and "T" simultaneously, then drag outside of the picture's bounding box to perform the rotation. To rotate in Picasa, you can right click an image in the editing window and click "Rotate clockwise" or "Rotate counterclockwise." For rotations of smaller angles click the "Straighten" item of the "Basic fixes" tab, then drag the slider in the editing window until the picture's horizontal or vertical edges align with the grid that Picasa has laid over the picture.
With Photoshop, you must define a text box to hold your label, while with Picasa you can type your text anywhere on your picture without such a text box. To label pictures in Photoshop, click the "T" icon on the tool palette, drag to grow a text box, then type into that box. To add text in Picasa, click the "Edit text" command of the "Basic fixes" tab, then click on your picture where you want to create text. You can rotate and size the text by clicking it to display the circular text gadget, then dragging to rotate and size the text simultaneously.
Both Photoshop and Picasa allow you to adjust contrast with a single click. For finer control, however, Photoshop offers a single "Contrast" slider, whereas Picasa has no explicit control for contrast. Instead, you adjust the tonal ranges of highlights and shadows. In Photoshop, adjust contrast automatically by clicking "Auto contrast" from the "Adjustment" menu. For finer control, click the "Adjustment" menu's "Contrast" command, then drag the "Contrast" slider to increase or decrease contrast. To adjust contrast in Picasa, you can click the "Auto contrast" button of the "Basic fixes" tab to tell Picasa to adjust the contrast for you automatically. To make your own contrast adjustments, drag the "Highlights" and "Shadows" sliders of the "Tuning" tab. For example, dragging the "Shadows" slider to the right will make the dark portions of your picture even darker.