| This scanning-help page is copied directly from the web, format and content has been edited. |
|
This scanning primer was written by the person responsible for the JenzScans collection. The content was taken from other Internet sources. I have changed the content to be more appropriate for web pages. JenzScans Scanning Tips Tuesday, May 27th, 1998 PART 1: Here is the first set of tips. It is fairly basic but I want to get everyone up to the same level of basic scanning. Some simple steps can improve the scans considerably. Some Advanced Tips are at the end. I have assumed that you will save the image at regular intervals! Some Very Basic Scanning Tips (amazing how many people miss these) 1. Keep the scanning surface of the scanner very clean. This saves considerable time cleaning the images later on. Occasionally wipe the surface with a soft cloth. Refer to your scanner documentation about cleaning the surface. Similarly make sure that the image to be scanned is free of dust, specs, pizza, etc. 2. Choose pictures carefully - a little planning can save hours of work especially when trying to merge images together to create fakes. 3. Always scan only the area you need for your final output. It saves time and memory. 4. Try to scan at a high resolution around 300dpi. Scanning at a high resolution helps avoid the color banding ( yellow streaks ) that can be seen on some scanners. This is a result of the way in which the printing process affects paper. You should not see this problem on proper photographs. If you consistently get yellow streaks drop me an email to discuss further. This problem is often seen in scanners that have a 3-light head rather than a pure white scan head. The Actual Scan 1. Place the image face down on the scanner. Make sure that the image is as straight as possible, as any rotating afterwards will decrease the sharpness and, for the same reason, use the controls in the scan software to alter brightness, contrast and Gamma if available. Goto FILE -> IMPORT (some programs use FILE -> ACQUIRE -> TWAIN ). This will bring up your scanners Twain Driver Dialog box, to scan the image. Make sure that the image type is set to RGB (or Color) and that the resolution is set to the required dpi. ( I always use 300dpi ). 2. Click on the PRESCAN button to scan in the twain window in order to select the section of picture you want to scan. 3. If the image looks dark, click on the GAMMA button, then either drag the slider, key in a value or drag the arrows to change the gamma setting and click OK. The main part of any image is made up of mid-tones, and gamma is the tonal contrast in this area. It is very important to correct the gamma at this point. This setting can make dull, washed-out scans look vibrant, and it is faster and easier to correct at the scan time rather than later. 4. Drag a box around the scan area in the preview window then click SCAN to make the final high resolution scan. 5. If you can avoid it do not run other applications in background whilst scanning unless you have a fast processor and/or tons of ram. 6. The finished scan is automatically loaded into your image software for editing. Save it immediately. You can now throw away or file the original. DON'T THROW IT AWAY before you've saved it. First Steps in Editing 1. You are now working with a large scan. If you have scanned from a magazine, the resultant image will have small "speckles" on it as a result of the printing process. We need to remove these speckles in order to smooth the image and get it ready for reducing for screen size. 2. Under the FILTER option of your graphics package will be a filter to "despeckle". In Photoshop this is FILTER -> NOISE -> DESPECKLE. Run the Despeckle Filter. This smoothes away the specs. 3. You can now either resample the image ( i.e. reduce it to screen size) or edit the image. I personally prefer to resample the image down to the size I want. I always resample to a resolution of 1024 pixels by 768 pixels. You do this by changing the image size. In Photoshop this would be IMAGE -> IMAGE SIZE. Make sure that you select RESAMPLE IMAGE BICUBIC if you have this setting. This is an intelligent way of working out the resultant image and yields the best results. 4. Now that the image has been shrunk to our final size we can begin to edit it. First of all we set the image highlights, shadows and mid-tones. To do that we use the LEVELS option. What we are doing is changing the image to have a good of color. Choose IMAGE -> ADJUST -> LEVELS. The resultant dialog box shows a Histogram of the spread. We first want to eliminate any area to the far left or far right of the histogram that is empty. A picture with a good range of all the tones will extend almost to both ends of the graph. The graph is actually showing the number of pixels for each tonal value. A low contrast image shows a large gap at the dark end of the spectrum ( left side) and a high contrast image shows a gap at the light end of the spectrum (right side). 5. To improve the image slide the left most slider (controlling the shadows) to the right. This has the result of darkening the shadows and therefore removing low contrast. Slide it to the first point where the Histogram begins to curve upwards. - i.e. it's not flat/empty. 6. Similarly, slide the right most slider (controlling the highlights) to the left. This has the result of darkening the highlights and therefore removing high contrast. Slide it to the first point where the Histogram begins to curve upwards. - i.e. it's not flat/empty. 7. Observe that the midpoint (mid-tones) automatically moves based on the left/right sliders. The whole image should now have improved and you have better tonal balance. It is amazing how many scanners do not do this. And, invariably, it is the biggest single improvement that can be made to a scan. Occasionally, particularly with very dark images, you may feel that you have lost some detail in the image. This can be brought back by experimenting with moving the middle slider. It is often a good idea to at least try sliding the middle slider left and right (using PREVIEW ON) to see the result. Experimentation is the key. When you are happy with the tonal range click OK. **Advanced Tip: Some Scanner software supports Level Histograms. It is better to use the scanner software. Try to get the best initial scan using advanced settings in the scan software, because every change made afterwards involves processing power, and some operations require a certain amount of interpolation which can result in a slightly less sharp image. 8. You are now ready to correct any errors on the image such as cracks, scratches, spots, text removal etc. We'll cover these in more detail later. Practice using the Levels and Histogram. 9. Finally use an UNSHARP Filter ( set at 15%) TWICE on the image to add sharpness back in that was lost during resampling. 15% is my favorite figure but you should experiment. You may like to try very large figures such as 80-110%. I personally don't like images that have been sharpened too much. **Advanced Tip: Sometimes if the image has a background of one color, say black or white, it can affect the histogram. Therefore, make a selection around the detailed image that does not include the background. Then use the levels adjustment histogram. This changes the selection, not the entire image. **Advanced Tip: If your graphics package supports adjustment layers (like Photoshop 6 & 5) use these to make your changes. This way the underlying image is not altered, which makes reverting changes back much easier. Similarly, in Photoshop 5, use the History list to remove unwanted changes. **Advanced Tip: If you are scanning an original 35mm photograph you don't normally need to run the "despeckle" filter. **Advanced Tip: If your graphics package supports Actions or Macros, set one up to automatically run Despeckle then Resample down to height 768. For narrow width, tall height images. Set another one up to automatically run Despeckle then Resample down to width 1024. For large width, short height images. **Advanced Tip: The TAB key toggles all on screen palettes ON or OFF. Handily the Shift+Tab combo does the same but leaves the Tool palette active. Great for making space. PART 2: You should now be able to scan, despeckle, and image size your pictures. In turn by using the levels options you can improve the tonal range and bring the colour out. Fixing Problems on the Image (Cracks, Rips and Scratches) Get to the point where you have scanned, despeckled and resized your image. Do NOT change the levels or Unsharp at this point (we can leave this until the end when we are happy with content). Removing Cracks or Joining 2 page images Cracks should be considered as very large areas of the image that are missing. This may be because the image is ripped or more commonly because the image spreads across two or more pages. The problem with a crack is that you have to replace a large volume of missing image with content that isn't there! A note on images that spread across two pages. Scan each page separately into your graphics package at a high resolution. Do not use despeckle, or image size yet. Check the size of both images and change the canvas size of one to be large enough to have the other image copied in. e.g. if you have two images 500x500 and the overall image should be side by side, change the canvas size of one to 1000x500. Copy the smaller image into the newer large canvas. Close and save the smaller one (just in case). Now use the move selection to carefully align the copied image against the other static image. Make sure that strong lines that cut across both images are aligned. (For example arms against a background are often a good guide, Hair also). Save the image ? **Scanning two images will use a lot of RAM, therefore close all apps that you do not need. If you have scanned the images from a magazine you might have a grey or white mark on a side of the image that is carried across into the new joined image. If this is the case use the magic wand with a tolerance setting of between 20 and 30 to select the edge. Once selected, delete it or clear it to transparent depending on your tool. You will then have to realign the image to ensure that the joins match. Save the image ? When you are comfortable that the images are joined as best as you can crop the overall canvas so that it contains just the picture, deleting any non-essential areas. Depending on your package link the 2 images together (in PhotoShop this would be by linking the layers), then run despeckle and resample the image size down to the correct final setting that you want. Depending on a number of factors (Quality of original image, Quality of Scanner) you will find yourself with either a) colours that match correctly across both sections of the image or (more likely) b) colours that do not match or are to dark. If the images match and you are happy skip the next paragraph. When the sections of the joined image do not match there are a number of tools that can be used. The tools are: Levels, Color Balance, Hue/Saturation and in Photoshop the variations palette. The best way to make use of these tools is to play with them and see the effect they have on the section that looks the worst. Use the Levels tool to darken/lighten the overall image and alter the midtones to try and match the other section. The Levels sliders let you gradually adjust the brightness, contrast, and midtones in an image. By adjusting the midtones, you can change the brightness values of the middle range of grey tones without dramatically altering the shadows and highlights. The Colour Balance command lets you change the mixture of colours in a colour image. Like the Brightness/Contrast command, this tool provides generalised colour correction. For precise control over individual colour components, use Levels, Curves, or one of the specialised colour correction tools: Hue/Saturation, Replace Colour, or Selective Colour. The Hue/Saturation command lets you adjust the hue, saturation, and lightness of individual colour components in an image. Like the Colour Balance command, this command relies on the colour wheel. Adjusting the hue affects and changes colour, representing a move around the colour wheel. Adjusting the saturation, or purity of the colour, represents a move across its radius. Practice with Hue and Saturation because they take time to understand but are VERY useful. They are perhaps one of the most ignored toolsets. The Variations command lets you visually adjust the colour balance, contrast, and saturation of an image or selection. This command is most useful for average-key images that don't require precise colour adjustments, or for fun changing areas of an image to different colours. By using these tools you can correct the image to match colours. Now that the colours are matched you will still have the crack running down or across the image. To remove this crack you should make use of the Rubber Stamp/Clone tool. Use a fairly large brush, and then clone sections of the image into the crack. Pick areas that are close to but do not contain the crack. Try and follow the flow of the material that you are cloning. For example if you are cloning a bed spread into a gap on the bed and the bed spread folds run left to right, use the clone/stamp tool in left to right movements not up and down. This is particularly relevant for rebuilding skin. When you have filled the crack use a small brush with a feathered edge to clone along the edges. The feathered brush blurs the edges and blends them together giving a more natural look that is not sharp. This the area where a lot of fakers go wrong they do not use the levels, contrast, variations nor do they use the feathered brushes! Save the image often as you make these changes or take history snapshots if you're using PhotoShop 5 or 6. Removing Rips and Scratches. To fix a rip use a small feathered brush and slowly clone using the stamp/clone tool areas either side of the rip onto the rip. This technique should also be used for improving repaired cracks in an image that were repaired as above. Do not use a sharp edged brush. You should use a small brush because the "fixed" rip tends to show up worse if you use a large brush. Textures that can make fixing rips difficult include lace, fishnet ? and detailed skin. Easy ones include water, metal, latex and leather <ooer>. If you use the brushes on either repairing the cracks or rips and it still appears artificial use a small - medium brush and the smudge tool. Set the smudge tool to an opacity of approx. 20% and gently run the brush along the "fixed" rip. This blends the rip edges into the background and improves the image. Scratches can be fixed in the same way as rips using an even smaller brush. Removing Spots Sometimes the difference between a good scan and a great scan is the cleanliness in the detail. Often I get scans where you can clearly see spots of abstract colour that should not be there. The deep black spot on the end of her nose for example! More often than not this can be very quickly fixed. To fix tiny spots select a tiny feathered brush. Choose ole faithful the Rubber Stamp/Clone tool. This time make sure that the Clone tool is set to "aligned" mode. The rubber stamp tool takes a sample of the image, which you can then apply over another image or part of the same image. Each stroke of the tool paints on more of the sampled image. Cross hairs mark the original sampling point. If Aligned is selected the sampling point stays relative to the clone tool i.e. it moves with it. The trick here is to zoom into the image to 400% so that the image is enlarged on the screen. Now methodically moving down and to the left move across the entire image cloning out any tiny spot that stands out. In this zoomed in mode the spots will be quite large and are easily replaced. Reset the Cloning tool sample point if the spots are close to edges that might otherwise get distorted. Don't be afraid of the zoom tool it is after all there to work in close-up on the image. Improving Specific Colours and Unsharp. Now that the actual content of the image is correct you can modify the colours and levels of the complete image as outlined in tips 1. In addition experiment with the colour balance, variations and level tools to improve the overall colour of the final image or selection. Have a try with the Hue/Saturation tool as this can fixed "washed out" colours. Run the Unsharp filter on the image twice as outlined in tips 1. This time use the selection tool to select the background areas, inverse the selection and run the filter on just the main area of the image. Is the background still taking away from the main image? If so select it and run a blur filter, or play around with the settings of a smart blur filter. If you find that the overall image is quite spotty try this technique: Select a huge feathered brush. Say the 100 one in Photoshop. Choose the smudge tool set to an opacity setting of 10%. Place the smudge tool on the spotted area. Press the mouse button down and with a VERY TINY movement rock the mouse back and forth a VERY SMALL distance. This smudges the picture together, removes the tiny spots but doesn't destroy detail. Add the detail back in by using a small feathered brush and the Sharpen tool. Run the sharpen tool along the areas that you want to add detail back into. I don't think this works on eyes particularly well tho'. Removing Text The techniques that have been used above can just as easily be applied to removing text. Again you have to use a variety of small - medium feathered brushes to clone away the text. If the text is on a single colour background then use the eraser tools to delete it. Save regularly. The big difference here is that text often covers materials and change in colour of a single material. For example in the Rolling Stone Cover of Sarah Michelle Gellar as Buffy The Vampire Slayer the text covers a blue mesh cape that changes in colour from Dark blue black shadows to light pale blue. Remove the text as best you can with the clone tool. Then use the toning tools (Dodge and Burn Tools) to correct the colouring. The toning tools consist of the dodge tool and the burn tool. Used to lighten or darken areas of the image, the dodge and burn tools are based on a traditional photographer's technique for regulating exposure on specific areas of a print. Photographers hold back light to lighten an area on the print (dodging) or increase the exposure to darken areas on a print (burning). By using a small brush, low - medium exposure settings you can blend, darken and lighten the image so that the textures look correct. This does take practice so don't give up the first time! The Opacity Setting When Cloning: Alter the opacity setting of the Clone Tool from time to time to get a softer edge and to enable blends that look more natural. A degree of practice may be needed to get the feel of the Clone tool. How far you take This process is down to choice and good taste. Always work on a layer copy of the image then if you don't like the results just delete it. |