(in PDF) describing my plugin and its many
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1. 130 image 382 4 After the Autostereograms plug in has finished deselect the 3D image channel to leave just your autostereogram showing The 3D channel remains in the Photoshop file for later use until you delete it using the channels palette You may now print it or do any other Photoshop operations to achieve further artistic effects The autostereogram shown was drawn at the low resolution of 72dpi to help illustrate quality issues As would be expected the 72dpi looks low resolution You can see steps A 6 A in the triangular eye guides When viewed as a 3D picture you will also see definite steps in the slope To the left of the autostereogram you may find it hard to get your eyes to follow the slope upwards and it may seem to drop down again This is an unnecessary problem you would normally avoid It is generally easy to do so but you may as well know you don t always get excellent results without experimenting a bit first Later parts of this leaflet give hints on drawing better autostereograms and hints on viewing them easily ALIGNED AUTOSTEREOGRAMS The plug in tries to copy the texture as faithfully as possible when it makes an autostereogram There are two ways to use the texture Normally the texture is copied stretched and shrunk a bit into the autostereogram The method used minimises the stretching and shrinking in the middle of the picture In other words you don t need to waste time makin2. Do not select the image alpha channel AUTOSTEREOGRAMS LICENCE This Adobe Photoshop 3 0 Macintosh plug in filter is supplied as is The user may work with the program in any artistic way whatsoever without limitation The program is licensed for use with one copy of Photoshop on one machine The program itself and associated documentation is copyright and must not be copied or reverse engineered or equivalent Although every effort has been made to supply a high quality product correct operation and performance with specific software or machinery cannot be guaranteed Liability for loss or consequential loss is not accepted Special versions of the filter may be created for particular customer requirements ABOUT THE AUTHOR Prof Harold Thimbleby is Director of Research in the Faculty of Technology at Middlesex University London He has been working with autostereograms since 1990 He has consulted widely and has been invited to speak at many conferences on autostereograms and optical illusions in the UK and abroad He recently wrote the entry in Microsoft s encyclopaedia Encarta 1997 CD rom for autostereograms Address Prof Harold Thimbleby Computing Science Middlesex University Bounds Green Road LONDON N11 2NQ Email harold mdx ac uk Phone 0181 362 6061 Fax 0181 362 6411
3. at screen resolutions such as 72dpi 1 Save your file in Photoshop format for future reference Saving a file in GIF format loses information which you will not be able to recover unless you save in Photoshop format 2 Convert the image to Indexed Color using the Mode menu 3 Delete the alpha channel containing the 3D image You can do this by dragging the alpha channel to the waste basket in the channels palette 4 Use File gt Save As to save the file as CompuServe GIF If CompuServe GIF is greyed out then you need to check you did steps 2 and 3 For the picture to work from HTML make sure the ending of the file name is gif A 9 A HINTS FOR GETTING GOOD RESULTS If an autostereogram does not work there are some obvious points to check 1 Did you use the correct channels when drawing the autostereogram See below for a summary of how channels are used for all features supported by the plug in 2 Ifyou see a rubbish 3D image this may be because you are over converging or over diverging your eyes You will find it helpful to use eye guides and ensure that when your eyes are diverged converged that you see exactly three eye guides Check by getting someone else to have a look 3 Your autostereogram may be too narrow It has to be wider than the 3D model 4 The 3D model may be too obscure or too abstract for most people to make sense of Try more recognisable organic or smoother shapes or even raise
4. channel though you can give it any name you like The autostereograms filter works by mixing the 3D model in the alpha channel with the pattern you have in the other channels When you have run the filter you would A 5 A normally hide or delete the alpha channel though often you will want to keep it around so that you can try other effects with the same model The 3D model itself is not changed when an autostereogram is drawn What you paint in the model channel as black is close what you do in white becomes distant Grey gives you intermediate depths Illustrated is a simple ramp going away from you to the right So to create an autostereogram you 1 Create a texture or pattern using Photoshop as usual You can import existing artwork fill with a pattern or to be quick use the Quick texture button in the Autostereograms plug in or just use the Noise gt Add Noise filter 2 Create the new channel for the 3D model image with the channels palette Use this channel to draw the three dimensional object You may like to call the new channel 3D image 3 After creating the texture and 3D image select all channels shift click on them and then use the Autostereograms filter Ensure that the 3D image channel is the bottom of the list of channels selected If you were using a monochrome image with just one channel for the texture and one channel for the model the two channels selected would look like this
5. method and provides no alternatives KPT s tool has an educational advantage over the current version of Autostereograms it provides a fast preview that you can look at while changing the eye guide separation You may therefore get an intuitive feel for the constraints on autostereograms and in particular the way in which eye guide separation can affect texture streaking See also the 3D Stereo Noise Apply Weiss Noise in the Texture Explorer in the obsolete KPT version 2 1 This allows you to use the explorer s range of textures but gives you no control over the autostereogram itself You don t even get to do the eye guides CHANNELS SUMMARY The Autostereograms filter uses channels The most common problems arising with the filter arise because the wrong channels are selected when using it Here is a summary of the channels and how they are used For drawing an autostereogram Select all texture e g RGB and image channels The texture should be in all but the last channel selected and the 3D model in the last channel selected For drawing a quick image The quick image is drawn into the last channel selected which is generally the alpha channel for the 3D model Of course the quick image works if only one channel is selected You get odd strange coloured results if you only selected RGB and forgot to select the alpha channel for the quick image For drawing a quick texture Select all texture channels e g RGB
6. several strips perhaps only decreasing accuracy in those strips that need help in improving the texture Wallpaper is particularly susceptible to streaking and often needs help by using a reduced accuracy though it is preferable to make the wallpaper wider or use the No background button which is described in the section on Wallpaper No background The error rate mechanism gives you no control over where the plug in discards parts of the 3D model It will give you an idea whether it is possible to redeem you design and get an autostereogram out of it Instead you can choose No background In No background the Autostereograms plug in ignores all parts of the 3D model that are white that is in the background You can therefore introduce the same effects as the accuracy but with greater control Parts of the image that you want to lie in the background you now simply make a light shade of grey anything other than pure white A more positive way of using the No background feature is to eliminate parts of an image for creative effects Speed There are many tricks to speed up the process of drawing an autostereogram Proofing in monochrome is about twice as fast as using RGB Using a simple monochrome noise so that you get the 3D model to work properly first is better than spending a long time designing a cute texture that is later found to be impractical Instead of monochrome you can use just one channel in any mode th
7. with the filter two eye guide A shapes You have to move your eyes to make them look like three spots either by going cross eyed or going boss eyed More precisely each eye sees two spots You move your eyes At first you will see four spots each eye seeing two You carry on moving your eyes so that eventually the left eye s right spot is on top of the right eye s left spot or if you find it easier the other way around You then see three spots Once you see three spots move your eyes onto the autostereogram and you should see it latch into place either above or below the paper depending on how the picture was designed Viewing autostereograms on screen is easier than on paper If you are viewing on paper try viewing in bright light When viewing on screen note that you must have an eye separation difference large enough to show up at screen resolution Try at least 0 25 inches If you are short or long sighted more or less equally in both eyes try removing your glasses If short sighted you then need to view boss eyed or if long sighted you need to view cross eyed COMPARISON WITH KPT S 3D STEREO NOISE Kai s Power Tools provides a simple autostereogram tool 3D Stereo Noise It is very limited the texture has to be random dots either monochrome or colour Apart from the eye separation and 3D image you have no creative freedom KPT s 3D Stereo Noise uses Autostereogram s stretch on right
8. ADOBE PHOTOSHOP AUTOSTEREOGRAMS 3D pictures magic eyes sirds autostereograms hollusions A powerful Adobe Photoshop 3 0 plug in filter for the Macintosh which draws three dimensional pictures from any suitable artwork Works in grey scale duotone RGB L a b CMYK and multichannel image modes Once drawn in Photoshop autostereograms can be modified in various ways to improve their artistic impact for example by adding text or frames The filter provides quick start features so you can draw your first autostereograms quickly In advanced modes it can draw wallpaper and other forms of autostereograms Autostereogram Autostereograms Method Requires a texture e g in RGB channels and a final alpha channel for the 3D image itself O Eye guides at top Style foreground triangle w EJ Eye guides at bottom 0 0709 in minimum J Advanced 0 0899 in maximum K Wallpaper EJ No background CL Minimal 1000 DPI horizontal resolution 1000 DPI vertical resolution o error rate Selection size 5 by 2 in Units INSTALLING AUTOSTEREOGRAMS The Autostereograms plug in filter is a standard Photoshop plug in which is installed in the usual way Drag the Autostereogram icon the plug in from the floppy disc to the Plug ins folder in your Adobe Photoshop 3 0 folder If you are running Photoshop you will need to quit it and start Photoshop again for the changes to take effe
9. adjusting the eye separation a tiny bit making it either larger or smaller Finally hiding streaks sounds more drastic simple delete them from the final autostereogram or duplicate a line above or below over them Eye separation The minimum and maximum eye separations determine how deep an image you create The deeper the image the harder it is to see at first but the more impressive it is when it is seen The range of depth covered depends most on their difference The smaller both numbers are the easier the image is to view but it must be looked at holding it closer to the face You can get autostereograms down to postage stamp sizes if you fiddle enough If you take the maximum separation much above 2 inches the distance between your eyes the autostereogram can only be viewed cross eyed or at greater distances If you go much below 0 5 inches for the maximum then you won t get much depth in the image If you put eye guides on an autostereogram try to make the part of the 3D image adjacent to the eye guides white in the model This means that the eye guides will be precisely the right distance apart for the person looking at the autostereogram to use them at that point You can use Photoshop to select both eye guides and move them elsewhere from where the filter draws them for example if you prefer them at the bottom left rather than in the bottom centre Textures A good autostereogram requires a texture that varies in c
10. at looks close enough to the texture you can test autostereograms just with that channel This will be faster than working with all channels at once Once you have got this channel to work nicely select the other channels and the 3D image and run the filter again with the same settings e g by pressing F The filter works line by line If you want to do tests on how your settings affect the texture quickly you can therefore select smaller parts of the image to work with Or you can do the top and bottom part of the picture in stages quite independently Once you get the hang of the filter don t bother to use it for the whole image but only select regions you are trying to get perfect Of course when you finally do the autostereogram you have do the entire image with the same settings Ways to scale Good autostereograms have nicely designed textures and this requires accurate scaling There are two easy ways to scale by hand or by giving measurement as numbers If you draw an autostereogram with eye guides you can use these as markers to help scale a texture accurately Select the texture you wish to scale and move it so that its left or right edge is aligned with the left or right eye guide Choose Effects gt Scale from the Image menu hold down the Shift key if you want uniform horizontal vertical scaling and drag the mouse so that it is over the other eye guide The selection will now be exactly the width of the e
11. ct There is no need to restart your Macintosh A 2 A QUICK STEPS TO YOUR FIRST 3D PICTURE 1 Create a new file e Select RGB mode e About 5 inches wide 4 high e Choose 72 dpi for speed or 300 dpi if you want to print a proof 2 Create a nice texture e Run the Autostereograms gt Autostereograms filter e Click the Quick texture button 3 Create a channel for the 3D image e Use the menu Palettes gt Show Channels to show the channels palette e Click kj in the channels palette to create a new channel 4 Draw a3D shape in the new channel e Run the Autostereograms gt Autostereograms filter e Click Quick image The quick image is a hat in a picture frame 5 Create the 3D picture e Shift click to select all channels in the Channels Palette e Run the Autostereograms filter again e Click on Eye guides either or both as you wish e Click OK to draw the autostereogram 6 Hide the 3D shape so you just see the autostereogram e Click RGB in the Channels Palette so you only see the RGB image 7 Stare at it or print it in the usual way FEATURES Quick start features Quick texture Quick texture Quick image Basic features Draws a simple texture to help get you started You should only have the RGB channels selected when you use this button The texture is designed so that it can be joined seamlessly It can be used to make tiled pictures and wallpaper Draws a simple 3D model in t
12. d background We ll use a marble texture Now choose symmetric aligned from the menu as the autostereogram plug in method and you will get a 3D butterfly image correctly aligned with the butterfly colours from the texture The illustration shows the result The autostereogram will work with just two copies of the repeating texture as shown here The width of this picture is twice the eye guide separation If you select Advanced features and set Minimal you can draw similar pictures without a background pattern WALLPAPER AND FLOOR TILES Wallpaper means a pattern that will work when printed on wallpaper there is a horizontal repetition in the pattern so that when rolls of wallpaper are used the autostereogram pattern matches smoothly across the joints Wallpaper is intended to be viewed with the paper running vertically and with the depth of the 3D image matching across the joins of the rolls of paper as well can be made by using the Wallpaper check box and a symmetric method To ensure an accurate match use the Offset tool and touch up the joints in the texture before running the autostereograms filter the Adobe tutorials describe the Offset filter to do this in order to create seamless patterns Although the filter will arrange for the autostereogram to run smoothly over the edge of the wallpaper you need to take several precautions e Abstract textures are much easier to get good results with otherwise the
13. d flat shapes 5 Your 3D model may be too complex If this is unavoidable use either of the asymmetric drawing methods and see which is better 6 This user manual has hints written throughout it Although this section gives most hints for getting best results you may find a solution to your problem in another section You can also fax email or phone Harold Thimbleby for advice contact details can be found at the end of this manual Autostereograms work by stretching and repeating the texture horizontally in clever ways to get the 3D illusion If a texture is stretched too much it is said to tear and has irritating vertical scratches in it If the texture repeats too much it is said to streak and has irritating horizontal lines in it Drawing an autostereogram involves getting the best results without getting noticeable tears or streaks Tears can be avoided or hidden To avoid a tear draw choose a higher resolution check that the 3D model does not have sharp steps in it try using the blur tool to smooth edges To hide tears blur the finished autostereogram or scale it smaller but don t forget to set the eye guide separations correspondingly further apart Streaks can be avoided or hidden To avoid streaks have fewer or more gradual depth changes on the affected horizontal lines rotating the 3D model often helps Streaks are very sensitive to the exact choice of eye separation and dots per inch resolution try
14. d tearing the texture and sometimes the texture gets completely messed up You can reduce accuracy to make the autostereogram s texture more like the original with no or fewer streaks or tears As you reduce the accuracy as you would expect the 3D image in the autostereogram A 11 A gets harder and harder to see You can compensate for this by increasing the resolution dots per inch to be higher than you require for the final image The number you type in the field can be zero which means no errors Otherwise the number means ignore one pixel of the 3D model every so many pixels Thus 1 would mean get every pixel wrong 2 would mean get every other pixel wrong 100 would mean get 1 of the pixels wrong And so on From this it follows that if you think you need to reduce accuracy you can try the following 1 You can probably do Undo in the Edit menu to restore the picture to its state before you ran the Autostereograms plug in 2 Use Photoshop to tell you how many pixels wide your image is You can do this by putting the mouse in the box in the lower left corner of Photoshop s document window and click the mouse while holding down the Option key 3 Choose Advanced in the Autostereograms plug in Otherwise the error rate is ignored 4 Enter an error rate about one half the width of the autostereogram you are trying to draw 5 If this does not help halve the number and try again You can draw an autostereogram in
15. er the image is to see If the separations are made small the image is easy to see but has little depth The autostereogram filter initially sets the separations to generally useful values You can set eye separation distances in inches centimetres or pixels The filter works internally in pixels and you may wish to use the accurate pixel values for instance with the Adobe Others gt Offset filter or KPT s Seamless Welder to help create good textures Method Uniform or symmetric stretching provides the best three dimensional image but in some cases distorts the texture excessively You have to experiment to get best results but start with symmetric as this is generally best stretch on left McA Symmetric symmetric aligned stretch on right Advanced features Click the Advanced button to enable the advanced features Eladvancea Wallpaper no background minimal and error rate You are generally advised to get an autostereogram design to work satisfactorily before choosing this option Wallpaper In the symmetric autostereogram drawing methods you can Ewetiparer draw wallpaper autostereograms which are designed to have a continuous texture They can then be printed on rolls of paper and the 3D effect will be seamless across the vertical paper joins The quick image button provides an image that is generally unsuitable for wallpaper No background White parts of the 3D model are treated as if
16. g the original texture look wonderful at the left and right edges of the picture since these areas aren t likely to be used You could draw a rainbow or a simple gradient fill across the picture as the texture to see which bits of it really get used The normal approach is easy to use and ensures the final autostereogram texture is as close to the original texture design as possible The alternative method copies the texture again making the centre best but making it fit exactly to the 3D model This is a more complex operation and which needs to be understood to exploit fully First create a new four channel document and create an autostereogram in order to get the eye guides Create a texture any way you like possibly using the Noise or Clouds filters your own artwork or even leaving the texture a uniform colour Paste a clip art image such as a butterfly into the RGB channels The important bits are to 1 Ensure the clip art is central 2 Scale it so it is smaller than the distance between the eye guides Then copy the image to the model and edit it so it has the desired 3D effects You can do this best using a layer so that the texture is not messed up in the process D gt Original butterfly in RGB channels taken Butterfly copied to the alpha channel and from Claris clip art redrawn with gradient fills to make the 3D butterfly have raised wings Typically you will want to put the image here the butterfly onto a texture
17. he alpha channel the last channel selected to help get you started The image is an optical illusion too it looks taller than it is wide but it is really the same OK draw the autostereogram Eye guides Eye guides at top Eye guides at bottom Style foreground triangle w 4 all Eye guide separation jo 7500 minimum separation 1 2500 maximum separation Units TREY pier A Uses the selected method eye guides and eye separation to draw the autostereogram The autostereogram will be drawn using the texture in all but the last channel which contains the 3D model The autostereogram will replace the texture Note that you can always use Undo to restore the texture and try different settings in the autostereogram plug in To make viewing autostereograms easier eye guides can be drawn at the top or bottom of the image or both the top and bottom You can chose whether the eye guides are drawn in foreground or background colours Eye guides can be either basic triangles or more distinctive arrow heads V arrow head or Y triangle Of course you can modify the eye guides in Photoshop later You can change background and foreground colours for the eye guides in the normal way using the colour selection box by clicking on the large squares Eye guide separation refers to how much depth an image can handle The greater the separation the greater the depths but the hard
18. is case darken the 3D model slightly so that there is no pure white background Then the No background feature can be used by introducing white patches on troublesome lines in the wallpaper you can very selectively relax the constraints There are no constraints on how the autostereogram wallpaper works vertically up the wallpaper You will normally want the texture and the 3D model to run continuously up and down the paper and you do this in the normal way perhaps using Adobe s Offset filter or KPT s Seamless Welder You can also design wall and floor tiles though you may find a non autostereogram border frame ends up looking better MORE CREATIVE IDEAS Posters can be made very easily You must decide what viewing distance you want to work with when experimenting Typically posters to be viewed up to 2 yards distance cause no special problems Large posters intended to be viewed at greater distances are quite tricky Surprisingly old people can see them more easily than youngsters With large posters try a plain e g grey border all around Try them at low resolutions e g one dot per inch or less You can use overhead projectors and acetates as a cheap way of testing posters drawn of course to scale on the acetate The World Wide Web can be used to display your autostereograms GIF is the standard format for graphics files and autostereograms can easily be converted to this format and they need only be drawn
19. it autostereograms are slightly easier to design 3D shapes Rounded organic 3D images work best Sudden depth changes are hard to see Try to make images that lead the eye slowly up slopes Things that are easy to recognise such as faces always work better than abstract figures that can be misinterpreted Narrow raised lines in the 3D model are difficult to see narrow lowered lines are even harder again lines running vertically rather than horizontally are harder Try to make lines at least 0 1 inches wide so that they are big enough to be obvious Forget lines that are only a few pixels wide unless you want special effects or have a skilled viewing audience Don t expect to get precise 3D shapes without a lot of practice A soccer ball may end up looking like a Rugby ball end on Fortunately few people will notice In fact the apparent depth of an autostereogram changes with viewing distance HINTS FOR EASY VIEWING Many recommendations for viewing have been published elsewhere We give a few additional hints here Certainly some people cannot see autostereograms As a general rule if you can see those 3D images using red green spectacles you will have no trouble with autostereograms provided you persevere If you don t view an autostereogram with your head horizontal i e in line with the picture you won t be able to see anything Try viewing autostereograms with eye guides usually two spots or
20. ontrast a lot horizontally such as a picture of a field of wheat or a row of trees A bad choice would be a texture of uniform horizontal lines starting with a streaky texture such as a venetian blind Actual texture colours don t matter much except to colour blind people contrast is far more important You can change colour mappings levels and so forth later after drawing the autostereogram Designing a good texture is tricky You can start by using the standard Offset Pattern and Fill tools To get accurate sizing so the repetitions merge nicely one method is to draw an autostereogram in a scratch window showing eye guides You can then use the ends of the guides as accurate markers to scale a texture to the exact size you want in another window If you align the left right edge of your selection with the left right eye guide you can drag the other edge of the selection so the mouse aligns with the other eye guide The best results are often achieved by designing the texture so that the tears or streaks are less apparent or appear a deliberate part of the final result The more noisy or blurred the texture the less obvious either tears or streaks become except in extreme cases Blurring will make the autostereogram harder to see noise will make it easier Bad texture Good texture Accuracy The autostereograms filter normally works with total accuracy This means that it makes no compromises when it comes to stretching an
21. stretching and matching may cause the texture to noticeably overlap in ways that you ll find difficult to eliminate e Make sure the depth of the 3D model is continuous around the edges otherwise there will be steps in the autostereogram when it is wallpapered If there are no horizontal cues in the texture such as horizontal banding the folk putting up the wallpaper on a wall with have a horrendously difficult job lining the paper up e The width of the wallpaper must be larger than three times the eye guide separation preferably as wide as possible The need to make the wallpaper work puts severe constraints on the autostereogram itself Therefore the Autostereograms plug in provides ways of relaxing the constraints but still allowing you to draw wallpaper e By setting No background you allow the plug in to ignore the background so there is less problem in making the background match up from sheet to sheet of wallpaper e By setting an error rate you allow the plug in to make mistakes The more mistakes it makes the better the wallpaper will look as wallpaper but the harder it will be to see as an autostereogram You can adjust the error rate to find a compromise for your design Generally you use the error rate feature when working at a higher DPI than you plan for the final artwork e The plug in s idea of error rate is random and the No background feature may be excessive for your concept In th
22. they are not No background there rather than at the maximum distance which otherwise provides a flat background for the picture The effect is that there is no distant image This feature is especially useful when drawing wallpaper Minimal White parts of the 3D model are not drawn in the Minimal AUtostereogram at all so the autostereogram is minimal Accuracy The plug in normally works at full accuracy but for creative 1000 error rate effects to make seeing autostereograms harder for instance you may wish to reduce the accuracy If the accuracy number is not zero every so many pixels in the 3D model will be ignored Having a low accuracy enables you to handle more complex shapes but they will be harder to see Note that low accuracy is most effective when the plug in is used at a higher DPI than you wish to print the results otherwise the low accuracy is visible in the result BASIC AUTOSTEREOGRAMS The quick steps to your fist 3D picture above takes you through the basic steps of creating an autostereogram We now explain how the autostereograms filter works so that the steps make sense When you understand how the filter works you will be able to control it for very creative effects Photoshop images have channels Examples are the red green and blue channels of an RGB image An autostereogram also needs a three dimensional model as well this has to be stored in an additional channel called an alpha
23. ye guide separation Another method is to copy or cut the selection and create a new document 38N Photoshop will by default create a new image the same size as the selection You can then use the Image Size in the Image menu to change the size of the image to any specified size Having done this you can copy the image and paste back to the original Note that when you have the texture in a separate window that wrapping the edges so that the texture makes a smooth join is easier When you have scaled the texture appropriately use Define Pattern in the Edit menu and then fill the entire image using Fill Once an autostereogram is drawn don t rescale it too much If you must rescale an image check it still works Size Autostereograms cannot draw 3D images right up to the left or right edge As a rule of thumb leave at least an eye guide s separation space around the 3D image The quick image that comes with the filter shows you how close you can get to the edge with the current settings you ve selected For the same reasons once an autostereogram is drawn don t clip its left or right edges because you risk losing more of the 3D effect than you anticipate You can mask out any parts of the autostereogram for pretty effects e g to overlay directly readable text but do not get closer than a couple of inches horizontally to the 3D effects you want to retain Landscape autostereograms are slightly easier to see Portra
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