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![\"\"](\"http:\/\/dianajuncher.dk\/astrophoto\/wp-content\/uploads\/2011\/03\/overview.jpg\" "\\"Photoshop")
<\/a>The Photoshop workspace has a menu bar at the top, a tool box on the left and a series of menu boxes and windows on the right.<\/p>\nBefore we begin, you need to know the following:\u00a0To open a file go to File > Open<\/span>. To save a file go to File > Save<\/span>.\u00a0To undo an action go to Edit > Step Backward<\/span>. To activate the guiding grid go to View > Show > Grid<\/span>. To convert a background to a layer (all images are opened as backgrounds), double click on it in the layer menu on the right.<\/p>\n Rotating 2. Go to Edit > Free Transform<\/span>. This frames the image in a box and you can then click and drag its corners to rotate it. Note that the image has to be a layer for this to work. Finish by clicking the check symbol in the free transform menu.<\/p>\n Cropping<\/strong> <\/p>\n With hue and saturation you can adjust what colors appear in the image and how strong they are. \u00a0To adjust them go to Edit > Adjustments > Hue\/Saturation…<\/span> and drag the pointers until you are satisfied.<\/p>\n Sharpening <\/p>\n
\n<\/strong>Rotating the image is a simple technique that can make horizons horizontal or turn the image upside down. I know of two ways to do this in Photoshop.<\/p>\n1. Go to Image > Image Rotation<\/span> in the menu bar. From here you can choose to rotate the image 90\u00b0 or 180\u00b0 or you can select Arbitrary…<\/span> to choose any angle you like.<\/p>\n
\nTo frame the image exactly as you want it, you can use the crop tool. It is located in the tool box on the left. Just select it and draw a box around the part of the image you want to keep. You can always make minor adjustments after you have placed the initial box. \u00a0Finish by clicking the check symbol in the crop menu.<\/p>\n
\nBrightness, Contrast and Color<\/strong>
\nSometimes the image can be improved by tweaking the brightness, contrast and color.
\nBrightness refers to how much lightning is applied to an image while contrast refers to how much shadowing there is. To adjust them got to Edit > Adjustments > Brightness\/Contrast…<\/span> and drag the pointers until you are satisfied.\u00a0Most deep-sky objects are fairly low in contrast and increasing it can greatly improve their visibility.<\/p>\n
\n<\/strong>Most images lose sharpness when they are shot because of the blurring filter in front of the sensor and because of atmospheric seeing effects. Some of the sharpness can be restored by sharpening the image, but you have to be careful: while sharpening makes the stars crisper it also exaggerates the noise. To adjust the sharpening go to Filter > Sharpen > Sharpen<\/span>. You can do this as many times as you want – in general it is better to apply a little less sharpening than you think you need.<\/span><\/p>\n
\nResizing
\n<\/strong>In Photoshop you can resize your image by either changing its physical size or its resolution. My camera produces images with dimensions 3456 x \u00a02304 pixels which is too large for pretty much everything except printing. To resize the image go to Image > Image Size…<\/span> and choose the new size. Unless you specifically tells it not to, it will conserve the proportions of the image. I prefer a width of 800 pixels for the images I put online.<\/p>\n