We’ve reviewed small Mac apps that edit, convert or compress images in a few formats, but finding an app that converts and compresses images between a large number of formats, and that too, for free, isn’t easy. XnViewMP is a Mac app that compresses images in JPEG, PNG, TIFF, BMP, GIF, JPEG-XR, JPEG 2000, PCX, PDF and TGA formats. The app offers a way to organize your images either into categories, or to add colored tags to them. It comes with a built in file browser that keeps track of file locations, and a color enhancer that allows you to adjust brightness, contrast, gamma, hue, saturation, lightness and to increase red, green and blue color levels. The app allows you to save a set of presets, and reuse them on an image. Changes made to an image can be previewed live.
The app has its own file browser and image viewer. All images you open are opened as tabs within the main app window, and you can easily switch between them. When you first launch the app, the browser view will open and you can start looking for images on your system. The app opens four windows (within the main window) by default. One for browsing files, one to see the categories, an image preview window and an image info window. The preview and info windows are populated only when you select an image. The info shows image properties and EFIX data, among other things. To add an image to a category, drag it from the browsing pane and drop it onto the relevant category in the category window.
From the file viewer you can adjust the color levels, hue, saturation, brightness, contrast etc., by clicking the third last button on the top bar. Move the sliders for brightness, contrast, gamma, hue, lightness and saturation, and adjust them anyway you like. To reset them to their original position, click the orange button at the end of each slider. If you want to save the combination of changes you made, click the save button next to Presets.
To set compression levels for an image, go to the File menu when viewing an image (in the app’s image viewer) and select Format Settings… For each of the file formats, there will be a different compression criteria, visit each format tab to see the compression criteria. When you save changes to an image, it will be saved and compressed as per these settings.
You can rate or label an image from the File menu as well. Select Rating & Color Label from the File menu, and choose an option from the submenu to categorize the current image. The app’s best feature is, no doubt, its ability to compress images for such a wide range of formats, and then perhaps secondary features like image labeling and format conversion are taken into consideration.