NASA has huge databases of photos, some numbering in the hundreds of thousands to millions. Most of them have been archived as-is for four good reasons. Archiving the images as-is preserves the historical quality of the images. The job of cataloguing and digitizing in various sizes and file formats is in itself a monumental task. Adjusting images can sometimes be rather subjective. Space is dark.

Many photo images from Nasa not only can be improved by but, also require adjustment. Simple steps can yield moderate to great improvements.

Sophisticated software or technique is seldom required to improve the images. Basic operations such as cropping, slight sharpening, and color/brightness adjustment, etc.are all that are neede and they are really no big deal. . It just takes a few seconds for each photo. Ulead Photo Impact or Paint Shop Pro or PhotoShop LE or Graphic Converter, (pick one), is all you need. If you don't have PhotoShop LE, which is free when bundled with many Adobe products, and don't want to take the short amout of time to download Graphic Converter, you could use just about anything to crop and brighten the images. Even Microsoft's PhotoEditor which comes as system software. Having used PhotoShop since the test beta of PhotoShop version 1, we just can't imagine not using it. Although it isn't usually considered a sharpening tool, the PhotoShop variations filter cleans images up nicely, often having the effect of sharpening the image as well or better than the sharpen or the sharpen edges plug-ins themselves, although it isn't usually considered a sharpening tool. And the pixel damage caused by excess sharpening is avoided. Usually the color levels and edge sharpening are slightly adjusted as needed for NASA images and for other images as well.

For those who may be unfamiliar with these basic operations we have included some screen shots.

Basic color adjustment with Variations PhotoShop filter. We have often said that the non-indexed full color image which can not be improved with the variations filter of PhotoShop does not exist.

You will brighten excessively dark shadows and ease excessively bright highlights. This will simultaneously enhance the image's color distribution and make details appear more clear.

Step1: Open file in PhotoShop. Select the Image menu, then Adjust, then Variations.

Step2: You will see this dialog box. Let's start with lightening the excessively dark pixels. It's pretty much self-explanatory. Always be sure to select the box for Show Clipping. With the radio button beside the word Shadows checked we can see lots of bright colors in this example image downloaded directly from NASA. This means that the darkest pixels, the Shadowsare way too dark. So you click on the thumbnail on the right hand side which says lighter. With the slider set in the middle between Fine and Coarse you will lighten the darkest pixels significantly. When you click on the thumbnail for lighter, the bright colors disappear, meaning that the clipping has been eliminated. You will also notice that you can now sse a lot more detail in the image thumbnails.You're ready for step 3.

Step 3: Darkening the lightest pixels, the Highlights, which may be clipped or excessively bright.

Click the radio button beside the word Highlights. The lightest pixels which are excessively bright or exhibiting clipping, will be very brightly colored. Click the bottom thumbnail on the right hand side which says Darken and the bright coloration disappears. You are finished with a basic color adjustment with the Variations filter. Of course you may still adjust the individual hues and/or midtones and/or the saturation in a similar manner if you find it helpful. Click OK. Save if you are satisfied with the results. Undo if you are dissatisfied with the results. This operation significantly improved 97 of 104 public domain images were downloaded from the web including NARA images, PHIL images and NASA images, or which were used from one of many stock photo image CDs purchased.

Adjusting Levels

Using Command+L for Mac or Ctrl+L for Windows brings up the Levels dialog box. The quickest way to see if the levels are satisfactory or not is to click on Auto. If you click on that and there is stiil not enough brightening, the middle triangle on the slider can be moved to the right. This will brighten the mid tones. A little movement can have a large effect so move the triangle in small increments. The changes to the image can be seen as the sliders are moved if the Preview box is selected. It is generally best to modify input levels using the top slider rather than output levels using the bottom slider. But this can be determined case by case. Modification of output levels more often results in flattened, clipped or washed out levels.

Sharpen Edges plug-in filter.

To sharpen images select Filter, then Sharpen and then select the degree of sharpening desired. Most of images we worked with benefit most from the lightest sharpening provided by the Sharpen Edges plug-in filter. Full Sharpen is often excessive. Images which seem to require Sharpen More are few.

Resizing images:

First applying one of the sharpen filters and and then resizing large images at least moderately downward is a good way to increase image clarity. Not always but, sometimes it is also possible to successfully enlarge an image by first greatly increasing the image dimensions, applying a filter and then downsizing to a size which is larger than the original. For example, start with an image of 300x300. Resize to 3,000x3,000. Apply filter(s). Resize back down to 400x400.

For full color formats such as tiff, jpg, tga, bmp, pict, downward resizing is generally safer than upward resizing. Color indexed images such as gifs must be changed to full color mode to resize, either or downwards upwards. For indexed images, especially ones with transparent areas, upward resizing is not recommended. An exception to this general rule would be of course when utilizing a good vector application. Xara X? Yes, Xara X is not only good. It's the best one. Why is vector so good for some operations? Because each and every file type is imported into (a vector application such as) Xara X and is then changed to an object while simultaneously exchanging the original low level resolution for a much higher one. PhotoShop, for example has a max resolution of 1,600%. Xara has a max resolution of 25,000% Transparency? Layers? You only think about them as being problematic when you use traditional pixel based applications. When you use vector applications, pixel based graphics applications such as PhotoShop or Graphic Converter are still required but only as a sort of helper application.

Try this. Open any file type of any size on PhotoShop. Pick any pixel in an area in which it can be specifically identified and compared after zooming to a magnification of 1:16. Next, open the same image in Xara. Zoom on the same pixel to 1,600%. First, you will notice that the pixel may not necessarily be one solid color but is graduated in color especially if the pixel is at the edge of a transparent area. In which case the pixel will not even be square, but rather it will be rounded off. Next you will see that you can zoom on the pixel to more than 25,000%. And the pixel can be edited in increments of 100 units on both the x and y axes. You can adjust the pixel itself as though it theoretically had 10,000 smaller parts. High resolution? Yeah, buddy. Output of images is still in the form of the usual traditional file formats which have real-world pixels, however.

But, hey, this discussion is not about vector based applications so let's get back to the subject.

We often discuss the differences
between various files types such as .tif or .jpg with people from the Bristol Biomedical Archive, the Amarican Society of Microbiology, National Geographic Society, PhotoDisc, TalkGraphics.com, NASA, CDC, NIH, Wadsworth.org, NARA.gov, Mac and PC club members, and many others. We will discuss tiff and jpg viz NASA images separately. Click the blob for that.

We are often asked, "Is larger pixel size always better?" This is not necessarily the case. For detailed professional purposes, generally, yes. But professionals also have different requirements and equipment to help meet those requirements than average internet surfers. For most viewers surfing the internet, a good clear picture which loads within a reasonable time and which remains not only within the web page layout borders but, also within the boundaries of the table cell in which it is placed is what is desired. Under these circumstances more moderately sized images have more clarity and usefulness than extremely large ones. If a downloaded image is too large one needs to scroll or to zoom out. Either way the supposed advantage of large pixel size can be lost.

Due to the manner in which images are initially created there are all manner of artifacts which can be inherent in the images. Lines both vertical and horizontal, checker patterns, moire, circles, speckles, blips, blobs, rays, glares, fuzziness, graininess, etc. may be present. Larger pixel sizes for many NASA images often exaggerates these imperfections making them worse.

Monitor screen size is also a factor. The supposed advantage of larger pixel size can be diminished by larger screen sizes. As monitor screen size increases the distance between pixels necessarily decreases. Resolution decreases. This may be advantageous or disadvantageous. An image with various rectilinear patterns or graininess will benefit from the smoothing or blurring effect of larger screen size and greater pixel density. A blemish free image with no real imperfections on the other hand often becomes stunningly beautiful at a smaller screen size. The pixel size which will fit entirely within the clearest screen size which has the most clarity, i.e., the screen size of 640x480 pixels at 24 bits, is just a little less than 640x480 pixels. Images should be examined at this resolution for defects and clarity. ( Do as we say, not as we do? Ok then, If you have time....) The most common screen size as of 2001 is 800x600, with the next most common being about equally split between a size up and a size down at 640x480. Viewers will change to increasingly larger sizes in the future. But as of this point in time if your image is sized no larger than 640x480 pixels, every monitor will be able to see all of it with less zooming out or scrolling.

The following images are for you to compare. If you can see that the adjusted image on the right is lighter with much more detail than the before picture, that is good. If you can tell that the image on the right has been sharpened just a little too much, your eyes and your monitor are fine.