gThumb is an image viewer and browser written for the GNOME environment. It lets you browse your hard disk, showing thumbnails of image files and viewing single images in many formats.
gThumb supports common graphics formats like JPEG, GIF, TIF, and PNG.
Less common image types (e.g., TGA, ICO, BMP, XPM) can be displayed if the supporting libraries are installed.
Some support for RAW image formats is available, especially with dcraw installed.
Additional features include:
Adding comments to images
Organizing images into catalogs
Printing images
Creating slideshows
Setting desktop backgrounds
Photo import tool for cameras and memory card readers.
Can read EXIF, XMP, and IPTC metadata embedded in files.
Supports extensions or plug-ins to extend functionality.
How to Extend the existing gthumb functionality
gThumb has a plug-in system for extensions.
Some standard features are implemented as extensions and are included in the standard distribution.
Users can write and share additional extensions.
Enable or disable extensions using Edit ▸ Extensions.
Some extensions have Preferences that can be modified from the Edit ▸ Extensions dialog.
This manual assumes that standard extensions are enabled.
If a feature seems missing, check which extensions are enabled.
File management Operations
Browsing Your Files
Copying and Moving Files
Filtering Files
Manual Fullscreen Mode
Opening an Image
Printing Images
Renaming Files
Sorting Files
Thumbnail Pane
Using Bookmarks
File Browser Options
Menubar: The menus on the menubar contain all of the commands that you can use in gThumb.
Toolbar: The toolbar contains a subset of the commands accessible from the menubar. The Tools button includes functions for batch processing multiple images.
Locationbar: The locationbar displays the current folder or catalog name.
Folder Tree: The folder tree allows navigation of the filesystem.
Single-clicking a folder loads its images in the browser view.
Double-clicking a folder, or clicking the expander arrow, lists the folder's subfolders in the tree.
Browser View: Displays images in the current folder or catalog.
Single-clicking an image enables the Information Sidebar for that image.
Double-clicking an image opens it in viewer mode.
Double-clicking with the middle mouse button opens the image in fullscreen viewer mode.
Organize Button: Located just above the browser view, this button allows grouping images into catalogs.
Statusbar: Displays information including:
Total number of images in the current folder or catalog and their total size.
Number of selected images and their size.
Properties of the currently focused image.
Information Sidebar: Displays detailed information (such as EXIF or XMP tags) about the selected image, located below the folder tree when a single image is selected.
Filter Bar: Located just below the browser view, it provides an image filtering tool. It can filter displayed images by characteristics such as file size, date, name pattern, and more.
Copying and Moving Files
Cut and Paste:
To copy a file, use Edit ▸ Copy or press Ctrl+C.
To move a file, use Edit ▸ Cut or press Ctrl+X.
Navigate to the destination folder using the folder tree, then use Edit ▸ Paste or press Ctrl+V to complete the transfer.
Drag and Drop:
Drag a file (with a left-mouse click) to a destination folder to copy it.
Hold down the Shift key while dragging to move the file.
Using the middle mouse button to drag will prompt gThumb to ask if you want to copy, move, or cancel the operation.
File Copy / Move Dialog:
Select the files to transfer, right-click, and choose Copy to... or Move to....
This opens a folder-selection dialog where you choose the destination folder.
You can enable the View the destination option to automatically go to the destination folder after the transfer.
Opening an Image:
The browser view shows images in the current folder or catalog.
Double-click an image (or press Return) to open it in viewer mode.
Press Escape to exit viewer mode and return to browser mode.
A toolbar button, View the folders, is also available to return to browser mode.
A Thumbnail Pane can be displayed in viewer mode if desired.
Printing Images:
To print the current image in viewer mode, use File ▸ Print or press Ctrl+p.
To print one or more images from browser mode, select the images and then use File ▸ Print or press Ctrl+p.
Select the printer from the General tab in the print dialog.
Select the paper type from the Page Setup tab.
The Layout tab provides additional options:
Set the number of images per page and view a preview.
Add captions under images using a configurable font.
Choose captions from file attributes like the file name, date, or camera settings.
Reposition each image within its print area using controls on this tab.
Thumbnail Pane:
When viewing an image in gThumb, you can enable or disable the thumbnail pane, which shows other images in the folder as thumbnails.
This feature can be toggled using View ▸ Thumbnail Pane or by pressing F8.
The thumbnail pane can be positioned either along the bottom or the side of the main image, controlled via Edit ▸ Preferences ▸ General ▸ Thumbnails in Viewer.
Image Editing Operations
Color Adjustments
Enhance Colors: Automatically corrects white balance without requiring user adjustments.
Adjust Colors: Allows manual adjustments for:
Gamma
Brightness
Contrast
Saturation
Cyan/Red, Magenta/Green, and Yellow/Blue color balances
Equalize: Provides automatic histogram equalization with no user adjustments required.
Desaturate: Converts image colors into shades of grey (without changing the image storage format).
Negative: Inverts color levels to create a negative of the image.
Resizing and Cropping
Resize:
This allows you to resize the image. The image may be scaled to a certain physical size, or to a certain percentage of the original size. The aspect ratio may be locked to a specific value, or freely adjusted.
Crop:
This allows you to crop the image. Click and drag the mouse over the desired area of the image. The area may be locked to a specific aspect ratio, or it may be freely adjusted. A rule-of-thirds grid or golden-sections grid may be superimposed over the image for composition guidance.
Red Eye Removal
gThumb provides a Red Eye Removal tool. To remove a red eye, position the mouse pointer over the red eye and click on it. gThumb will attempt to remove the red region and replace it with a more natural-looking gray region. If the results do not look correct, press Escape and click on the Undo item.
This tool works best when there is a high color contrast between the red eye and the surrounding facial area. It does not work well for "orange eye"
Rotations and Flips
Mirror: Flips the image horizontally, swapping the left and right sides.
Flip: Flips the image vertically, swapping the top and bottom.
Rotate Right: Rotates the image clockwise.
Rotate Left: Rotates the image counter-clockwise.
Note: The rotations in edit mode act on the image in memory and are not direct file operations. For JPEG images, this means they are not lossless operations, resulting in slight degradation when the image is re-encoded and saved.
Batch Tools
Batch tools are provided to modify multiple images simultaneously. Changes are written immediately, and are not undoable.
Changing Dates:
To change the file modification times, the comment dates, or the Exif DateTimeOriginal tags of multiple files, select the files in the browser view. Then click the Tools button on the main toolbar, and select Tools ▸ Change Date.
Select the desired date options, and click Execute to complete the process.
Converting File Formats:
To convert one or more images into a new file format, select the images in the browser view. Then click the Tools button on the main toolbar, and select Tools ▸ Convert Format.
Resizing Images :
To resize one or more images using the same dimensions or scaling factors, select the images in the browser view. Then click the Tools button on the main toolbar, and select Tools ▸ Resize Images.
Then select the desired maximum output dimensions, or the desired percentage scaling, and the destination folder. Click Execute to complete the process.
Rotating Images Losslessly:
To rotate one or more images, select the images in the browser view. Then click the Tools button on the main toolbar, and select either Tools ▸ Rotate Right or Tools ▸ Rotate Left. The images will be rotated.
Automatic Slideshow:
Start a slideshow of the currently selected images by:
Pressing F5
Clicking the slideshow toolbar icon
Selecting View ▸ Slideshow
If no images are selected, all images in the folder will be included.
Modify transition effects and display time from Edit ▸ Preferences ▸ Slideshow dialog.
Some graphics cards and drivers may experience crashes with transition effects enabled; set the transition effect preference to None if you encounter issues.
Control the slideshow manually:
Advance to the next image: Down Arrow, Right Arrow, Page Down, or Space.
Go back to the previous image: Up Arrow, Left Arrow, or Page Up.
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