The original geese photo was 1600x1200 pixels. After cropping, the new photo size is 971x598 pixels. However, we want the picture to fit in a 250-pixel column width. To do that, let's use GIMP's scaling tool.
Figure 3, below, shows the cropped geese photo in the GIMP canvass widow at the top right and the GIMP Navigation dialog on the bottom right. Here, the + and - zoom icons (magnifying glasses) at the bottom of the Navigation dialog have been used to set the view zoom to 1:3 (one third size). That's so most of the image will fit into the canvass window.
At that 1:3 view zoom factor, the photo is larger than the size of the canvass window. So, the mouse was used to drag the Navigator dialog view box to center the geese on the canvass. Try setting different zoom factors and moving the photo around on the canvass.
View zoom and scaling are two related but very different things. Changing the view zoom does not make any changes to the photo or image you are viewing. It only changes the size of the photo or image in the canvass window.
On the other hand, scaling changes the actual dimensions of the photo or image that you are viewing.
Please notice the combo dialog box in the bottom left of Figure 3 has been toggled to show the Undo History dialog. You can lengthen that Undo History dialog by dragging the bottom edge of that dialog box down.
To scale the cropped geese photo, go to the Menu Bar on the canvass window and click Image > Scale Image to open the GIMP Scale Image dialog box. Figure 4, below, shows the Scale Image dialog box.
If you are using an older version of the GIMP that does not have a Menu Bar on the canvass window, alternate click (left-click if you are using a right-handed mouse) anywhere on the canvass. That pops up a menu. In that popup menu, click Image > Scale Image to open the GIMP Scale Image dialog box.
For this exercise, we are concerned only with the image's pixel size. Please notice that at the top of the Pixel Dimensions box in the Scale Image dialog box the fixed values for the Original Width and Height. In Figure 4, below, those values are 971 pixels and 598 pixels.
Please notice also the lock icon to the right of the Ratio input boxes in Figure 4. You can toggle lock and unlock mode by clicking on the lock icon.
In Figure 4, the aspect ratio is locked. That means that if you make a change in either height or width of the selection, the value of the other dimension is automatically changed so that the height-to-width ratio of the selection is maintained.
Because the width of the cropped geese photo is to be 250-pixels wide, 250 is entered into the New Width input box in the Scale Image dialog box shown in Figure 4. When the Enter key is punched, the new Height value is automatically set to 154 pixels because the aspect ratio is locked.
For your photo or image just do the same things. Go to the Menu Bar on the canvass and click Image > Scale Image to open the GIMP Scale Image dialog box. Make sure the aspect ratio is locked.
Then insert a value for the new pixel-width or pixel-height that you want for your photo. Hit Enter and the other dimension value automatically changes. Click OK and viola', your cropped photo or other image is scaled to the new dimensions.
Figure 5, below, shows our geese photo after scaling. Please notice the rulers in the canvass-screen at the top right of Figure 5 show the new photo width of 250 pixels. Also, the photo now is smaller than the canvass-screen size.
Meanwhile, the photograph is entirely within the Navigator dialog image display. Also, the scaling action has been added to the Undo History dialog.
For the geese photo example, the + zoom icon (magnifying glass) at the bottom of the Navigation dialog was used to set the zoom to 1:1 (actual size) in moving towards Figure 6, below. That's so the image fills the canvass window and we are seeing it as it will appear on a Web page when we make the brightness and contrast adjustments.
Overall, the geese photo in Figure 5 is a little too dark. So, let's brighten it up some.
To do that, open the Brightness-Contrast color tool dialog. Go to the Menu Bar on the canvass window and click Tools > Color Tools > Brightness-Contrast. Then the Brightness level is set to 36 and the Contrast level is set to 100. Please see Figure 6.
This brightness-contrast adjustment brings out the blueness of the water and makes the water appear more watery. However, there are tradeoffs when you do these sorts of adjustments. Please notice that although the photo overall is much brighter and livelier, the feathers coloration has changed and is somewhat faded.
Figure 7, on page 4, is the same geese photo with the Brightness level set to 40 and the Contrast level set to 30. The feathers are truer in color and detail to the real scene that was photographed. But it just does not have the zing of the rendition created in Figure 6.
There are editing tricks that could be used to have both the zing of the bluer, more watery, water and the truer, more original color and detail of the feathers in the same photo. However, those tricks are beyond the scope of this lesson.
To adjust the brightness and contrast for your photo or image just do the same things. Go to the Menu Bar on the canvass window and click Tools > Color Tools > Brightness-Contrast. Then play around with the brightness and contrast adjustment settings.
If you do not have a Menu Bar on the canvass window, alternate click anywhere on the canvass. That pops up a menu. In that popup menu, click Tools > Color Tools > Brightness-Contrast to bring up the Brightness-Contrast dialog box.
When you get your photograph or image just the way you want it, save it. To save your edited photo, alternate click anywhere on the canvas and then click File > Save As.
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