Manual

imageSynth 2 User Guide

If you’re involved with imaging—photo retouching, 3D rendering, game development, product and architecture visualization, and other fields—imageSynth is a powerful yet easy to use solution for creating seamless tiling textures from photos and other bitmap images. You can create, for example, a background photo or a texture for a 3D model that wraps from left to right and top to bottom so you can offset the image to highlight an area—never showing a seam. imageSynth can also be used to create larger resolution images— such as those used for motion picture background plates—from relatively small image sources.

imageSynth operates with all the interactive user input you’d expect from an image editing application. You begin a session by loading source images called seed images. Then you specify image chunks—parts of the seed images that contribute to the final target image—using the selection tools in imageSynth. You can also command imageSynth to auto-generate chunks from images. imageSynth supports 28 popular file formats—including HDR files—to use as source files. imageSynth also reads and writes images with transparency, such as PNG files, making compositing a breeze.

imageSynth 2 page 1 Luxology

imageSynth the plug-in, versus the standalone version 3

Hands-On with imageSynth 2 4

Getting Down to Business 6

Image Too Large 7

Making Chunks 8

Defining a Manual Chunk 10

Forcing Some Predictability 12

Output 13

Manual Placement of Chunks 15

Hands-on With Chunks: The Fun Part 16

Finalizing your Texture 18

Easy Alterations to your Texture 18

imageSynth in the Real World 20


imageSynth the plug-in, versus the standalone version

imageSynth runs on the both the Mac and PC. There are two versions of the software for each platform; a standalone version and a Photoshop plug-in version.

imageSynth’s user interface is nearly identical in the standalone and the Photoshop plug-in versions of the software. If you own Photoshop, you may never need to use the standalone version, but it’s very convenient if you don’t use Photoshop and want a quick way to generate tiling images.

By default, the standalone version begins with an image canvas of 1024 by 1024 pixels, but you can change this through the Options menu. With imageSynth as a Photoshop†-compatible plug-in, you set the size of the target image before making the Filter>Luxology>imageSynth 2 command. As a plug-in, it’s usually a good idea to define the image target layer as Transparent. By doing this, you have more flexibility whether performing touch-up work in imageSynth or with the host’s editing tools. imageSynth has no theoretical limitation for final rendering dimensions; your only constraint is the system memory you have available.


Hands-On with imageSynth 2

The best way to describe the workflow in imageSynth is through examples; the following sections guide you through the interface and the steps you take, from simple to more advanced seamless tile composition. In this first example imageSynth is used as a plug-in inside of Photoshop.

STEP 1: Get a source image or two located on your hard drive. The best images to use should meet two criteria:

• The visual content of the image suggests randomness and a diffuseness. Photos of rocks, leaves, sand, grass, even a mound of coins or buttons make good input images. The less distinguishable each object is in the photo, and the greater the distance from which you take the photo, the better. You don’t want your audience focusing on a specific element in your composition, although you’ll see that imageSynth’s edge blending work is quite undetectable. It’s simply not a good idea to allow a background texture in a scene steal from the foreground hero in your piece!

•Flat lighting is much better than lighting in your photography that suggests a light direction. Choose an image taken on a slightly overcast day, or use tenting if you are shooting a new source image indoors. The reason for this is that you can rotate chunks in imageSynth to better integrate photo sections; if you rotate a strongly-lit chunk with clearly defined shadows, your finished composition will look awkward and implausible. Most photorealistic scenes don’t have different sources of light casting every which-way every five inches.

STEP 2: In Photoshop, choose File>New. In the New dialog box, choose dimensions for your new image that are larger than the images you plan to use as seeds for your imageSynth chunks. If, for example, you have a 2592 by 1944 (5 MegaPixel) image you want to use as a seed, make the Width and Height in the New box greater than these dimensions; in fact, for your first time out with imageSynth—to get the best idea of the power of this application—make the New image 2 or 3 times the size of your seed image. Specify the Background as Transparent from Photoshop’s drop-down, and then click OK. In the standalone version, you can specify the target image size through the New Image command.


STEP 3: Choose Filters>Luxology> ImageSynth 2 from the main menu. The interface will look like this:

The callouts you see in this figure are your second stop; click Options. Here, you can set the Maximum Command Stack Size (which determines your Undo buffer) and the Maximum Thread Number, invaluable for quickly processing large images. imageSynth recognizes multi-processor configurations when you launch it.

Step 4: By default, imageSynth opens with the Input tabbed window in focus. Click Add Image and then browse your folder window for the seed image(s). Seed images appear in the left pane as a thumbnail preview with image dimensions listed after the file name. Hold Shift while you click images in the folder window to load several seed images at once. Note that the thumbnail contains a label called “chunk”, which is the same dimensions as the seed image. If you like, you can stamp (or command imageSynth to auto-create) a texture file using the entire image. However, this guide shows you shortly how to define a chunk, automatically or manually, that is only a section of the seed image, and this is where a lot of the power of imageSynth lies.


Getting Down to Business

The items on the right column of the interface are actually tear-off palettes that are by default docked to the UI. You can detach Tool Properties and Actions by dragging by the title bar off the UI, and they can easily be reattached by drag and dropping them back to their original location. The interface can also be expanded to

provide a better view of the preview/working window, as shown here.

When your cursor is in the Input and Output working windows, you’ll see tool tips directly below the window. Note that you, at various points of texture creation, will not want to view the window with scroll bars, but instead to see the whole composition in preview. To zoom out, follow the tools tip: zooming is performed by holding Alt/Opt and using the scroll wheel on your mouse or other input device.


Image Too Large

When you’ve imported a seed image that is larger than your target document size, you’ll see an attention box like this one:

Your options:

•Scale image down to fit within output- imageSynth dynamically scales a copy of your seed image (imageSynth doesn’t touch your original files) to its maximum possible size to use as a single chunk. For example, you’ve defined a new document at 800 x 800 pixels and the image you just added via the Add Image button is 2500 by 1024. Choose this option to scale a copy to no larger than the target image size, in width and height.

•Limit chunk size when editing-This option loads the entire seed image at its original size, but only accepts the maximum dimension of the target new image file you’ll be rendering to, although you can edit the position of the full-sized seed image chunk.


Making Chunks

If you wish, imageSynth can automatically define chunks based on seed images. However, before you jump ahead and click Generate in the Actions window, take a look at Figure 4, Individual Chunk Properties.

• Priority-By default the Priority is set to 1 for all chunks and you can see this in the list; you can also change Priority for chunks. Priority is how often imageSynth’s rendering engine “chooses” a chunk when you auto-generate the Output. After you’ve clicked Generate and previewed each chunk, let’s say there’s one chunk that’s okay, but not an outstanding part of your composition. You click the chunk title on the list, then use the spin controls or enter a new value manually in the Priority field, then hit Enter. You can assign a chunk a higher priority than 1 if you feel a chunk will be an important player in your composition, or decrease the value to, for example .5, so it occurs seldom (if at all) in your texture.


•Random Chunk Generation- imageSynth examines the seed images and then culls the number of chunks you specify. You can see each chunk marked by a green outline box (Auto chunks are always rectangular) in the preview window; isolate your view of the chunks by clicking their title on the list after you’ve clicked Generate. For this example, set the number to 3; it’ll be easier for you to then evaluate the results.

•Size of Chunk-The Auto Generate chunks function doesn’t scale parts of the seed image, but rather the percentage you define indicates the percentage of area of the seed image, sort of like carving a slice from a pie. If you specify 75%, for example, each of the three chunks will be bounded to 75% of the area of the seed image.

High Pass Filtering is offered in imageSynth as a convenience (bullet 3). High pass filtering can help reduce the noise in highly compressed JPEG images and noticeably noisy scans of film photography. It should be noted here that Photoshop’s own Filter>Other>High Pass is more sophisticated and if you own Photoshop, you might want to run a High Pass on the seed image before beginning an imageSynth session. High Pass is not recommended on an image that’s not noisy, it can visually flatten your photograph (which can produce a visually interesting special effect), and the Filter Size in imageSynth determines the strength—low values knock the daylights out of your photo, higher values produce a much more subtle filtering.

Now click Generate and remember that this isn’t the fun part yet: you’re still in the Input window and the stage of creating chunks. Let’s say you anticipate that you’ll need a specific chunk based on a particular image area that wasn’t defined by auto-generating chunks. This is what the Tool Properties palette is for.


Defining a Manual Chunk

Before you begin manually chunking away, you need to first click the seed image thumbnail at the left, and then click the New Chunk button. Doing this generates a new chunk based on the entirety of the seed image, shown as bullet 1 in Figure 6. Now you get to work—

You have two selection tools: the rectangle and the lasso, shown at the top of this palette as icons, bullet 2 in Figure 6. The rectangle selection works completely predictably: you click and diagonal drag in the Input window to define a rectangular chunk—everything outside the green highlight onscreen is dimmed and excluded from the chunk selection. Notice that there are selection mode button below the tools: Standard, Add to Selection, Subtract from Selection, and Intersect. These are the same Boolean operators as used in Photoshop’s selection tools on the Options bar. You can create quite elegant selections and pinpoint the photo element you want as a manually created chunk. The lasso tool is probably your best bet, for example, to isolate distinguishing elements in a picture; as you can see in Figure 5, the clump of mulch in the image is visually interesting and can be repeated in the final texture several times by making it a chunk. The lasso tool’s visual appearance onscreen is a little different than Photoshop’s Lasso tool, but operates the same way. You draw around an area and when you release the mouse button the lasso shape


auto-closes at your first click-drag point. The area is highlighted with a green tint during the process, a good visual indicator.

Note: You can use the standard keyboard command of Ctrl/cmd+Z to undo an operation, and also use the Undo/Redo button at the top of the UI. If you’re thoroughly dissatisfied with a manual chunk (or an automatically created one), click its title on the list and then click the Delete button. You will not get a confirmation box on the delete, but clicking Undo will restore the chunk to the list.


Forcing Some Predictability

To the right of the Boolean tools is the Forced button. Because random placement is the opposite of predictability, the green area you drag to define a chunk might—or might not—appear in its entirety when you auto-generate a texture image. However, you probably want on occasion to make absolutely certain a flower or a specific pebble is included in your texture; this is what the Forced option is for. When you drag or lasso to define a chunk in normal selection mode (not Add to, or other Boolean options) you preview a green interior tint over the selected area. When the forced button is clicked and then you select, the tinted interior is red, indicating that the chunk you’ve defined will definitely appear as a chunk in its entirety when you eventually stamp your texture.

An even more sophisticated definition move is to first select a chunk area without the Forced option: as you select, the area is tinted green. After making the selection, then click Forced and use normal Boolean mode to drag inside the currently defined chunk. As you can see in Figure 7, the outer edges of the stone will probably be used in the final texture synthesis, but the red area—defined using Forced—will definitely be used. Think of it as a sort of “feathering” edit. You have effectively provided imageSynth some optional “pad” to use when stamping the chunk which will improve it’s integration to the rest of the image.


Output

Now that you have chunks galore, it’s time to apply them to the target image.

Click on the Output tab now. Notice that there are Stamp and Eraser buttons, which call the corresponding tools, just above the working window. You won’t use these tools just yet—let’s try an auto-stamp process before getting into more elegant and refined texture synthesis.

In Figure 8 you can see highlighted the options for Auto Stamping.

•Placement- The options here are Random and Semi-Regular. The options in this drop-down are self-explanatory to a degree: The Random choice activates the Jittering percentage option and by default Jittering is set to 0% producing a fairly unpredictable pattern. However, there’s an imageSynth process after this process that fills in any gaps in the output image with completely unpredictable chunk distribution. The Semi-regular option places the chunks you’ve generated starting at the top left and working its way to the right until it reaches the end of the row. At this point, the placement returns to the left side of the main image and begins again.

•Covering Factor-This option is available when Semi-Regular is chosen as the Placement method. Cover Factor determines the percentage by which chunks overlap neighboring stamped chunks in your composition. The default percentage of 25% is usually a good one, providing an adequate encroachment on placed chunks while retaining the uniqueness of the new stamped chunks toward their center.


Click Start now and see what the rendering engine does with the automatically and manually-defined chunks in the auto-creation process.

Tip: Once you’ve clicked the Start button, you can cancel at any time: the button toggles to a Stop button after you first click it.


Manual Placement of Chunks

Let’s suppose you’re 99% pleased with the automatically generated seamless texture you’ve just created. To get that other 1% addressed, this section shows how to first erase part of a texture area, then how to manually stamp replacement chunks. You have a number of options described here; check the tool tips once your cursor is inside the working window.

Using the Eraser

When an area of your Output window is completely covered with opaque chunks, the Stamp tool cannot place any more chunks. This is when the Eraser tool comes into play. When you click the Eraser button, you have Square or Disc as the shape (available on the panel to the right of the working window), and the Size slider. Erase what you want to replace in the working window, then you’re all set to manually stamp a new chunk (see Figure 9).


Hands-on With Chunks: The Fun Part

There is a lot to cover in this section because there is so much flexibility when it comes to stamping a chunk.

First, placement of a chunk is the key to making the best-looking texture. Although imageSynth is quite good at hiding edges of neighboring chunks, it’s you—the designer—who not only makes the judgment calls, but also needs to guide imageSynth, matching more obvious edges between chunks. For example, it’s not the right use of imageSynth to stamp a chunk that features the soft curves of a leaf into neighboring chunks that feature the straight stems of other leaves. imageSynth won’t be able to aesthetically reconcile the clearly different geometries in the chunks.

Therefore, your approach to manually stamping an area is to try to align the chunk’s visual content with the existing Output content in the working window. This is done by moving, scaling, and/or rotating the chunk you’re going to stamp into the window. Notice that as you hover your cursor, loaded with a chunk you’ve chosen from the list, your preview of the chunk is semi-transparent (see Figure 10), making it very easy to align the chunk’s visual content with surrounding areas. ImageSynth can deal with a ballpark stamp placement—when you click, you don’t have to be exactly over and area that needs alignment—come close when you click and imageSynth will perform the best calculations.


It should be pointed out that you can scale a chunk up to 200% of its original size, but no application today can intelligently add data to a pixel-based image, so you might see a little loss of focus if you increase a chunk size to greater than 100%. It depends on the composition and many times you can get away with one or two chunks that are enlarged.

To scale a chunk:

• Hold Shift and then use the scroll wheel. Pushing the wheel away from you enlarges the chunk; pulling toward you with the wheel shrinks the chunk, or

•Right-click to use the pop-up menu. Scaling choices from the menu are limited to 2x and x/2, but you’ll also find a convenient command on the pop-up: Reset. If you’ve been Shift+scrolling up and down for a while, you’ll find it a nicety to be able to restore a chunk to 100%, its original size.

Rotating a chunk is also indispensable for aligning the new chunk with existing ones in the working window. You can:

•Hold Ctrl/cmd and then use the scroll wheel to rotate the chunk. The number of degrees and precision is limited only to your input device driver’s controls and the resolution of the mouse (or other pointing device such as a stylus).

•Right-click to access the pop-up menu. The Reset command is invaluable when you’ve been rotating with your input device to straighten your chunk. Also, you have 90CW, 90CCW, and a full 180 rotation command using the pop-up.


Finalizing your Texture

Once you’ve filled the working window, it’s time to click Apply—the button at top left renders the composition to the document window you created in Photoshop, or the default document in the standalone version. If you’re using the standalone version, you’ll need to save your document; similarly in Photoshop you use File>Save to save the seamless tiling texture.

Especially if you’ve worked on a texture that has white or near-white elements, you might not know whether you’ve completely covered the Output area. This is why it’s important to zoom out until the scroll bars go away (hold Alt/Opt and use the scroll wheel) to examine your work before clicking Apply. If you don’t, not to worry: you’ll get an attention box that tells you, “The output is not complete. Are you sure you want to exit?” Click No to finish your work. It’s also possible you don’t want to finish the Output, and that you have a design need for an empty area of the texture. An incomplete texture will not seamlessly tile correctly, but you’re in charge: click Yes and your texture is rendered to a document window. If you rendered to a transparent layer in Photoshop, you can now easily complete the document with Photoshop’s paint tools or Clone Stamp tool.

Tip: Use Behind painting mode in Photoshop with paint tools, when completing an incomplete imageSynth rendered texture. By doing this, no pixel in the texture that imageSynth created will be changed.

Easy Alterations to your Texture

Only you know and can decide the purpose for your imageSynth seamless tiling texture: we show a few novel uses in the next section. If the center of your texture features visual content that you need to move, you’re in luck because the texture can be offset and there are no gaps or seams. If you’re using Photoshop, you’re in luck twice today: to move the texture around so that little twig or orange leaf is a little to the left, you choose Filter>Other>Offset, as shown in Figure 11.


Drag the Horizontal and Vertical sliders, Photoshop offers a live preview in the document window, and choose Warp Around as the Undefined Areas option. Click OK when you’re satisfied and you’re off to finish a project.


imageSynth in the Real World

Although desktop wallpaper is a fine use for your finished texture composition, you probably have larger plans and needs for your work. The following sections take a brief look at real commercial needs and how they can be addressed through imageSynth-generated images.

imageSynth for Desktop Publishing

With the ever-increasing need for color printing and print-on-demand, the stakes have been upped for professional quality collateral material such as brochures, flyers, and menus. In the competitive world of business, advertising simply doesn’t cut it with a one or two color print job. ImageSynth is an ideal resource for backgrounds in desktop publishing documents, to cover areas with lush detail that used to be filled with a flat process color or a simple gradient.

This mockup of a restaurant menu uses an imageSynth tiling texture of a close-up of grass, with overlaid semi-transparent elements to better integrate the composition. Offsetting the grass texture was easy using Photoshop to put irregular elements in exact locations on the pages, avoiding an awkward look when the grass texture might compete with the text.

A repeating texture of a basketball for a sport brochure, a seamless texture of coins for a financial institution: imageSynth lets your imagination keep the edge over competing design houses.


imageSynth in Game Development and 3D IllustrationMost advanced modeling/rendering applications today can map a 2D image to local or global

3D space, making it an easy task to fill in parts of a scene with objects that look complex but really aren’t (the 2D image is driving the visual complexity). With an imageSynth texture applied to a 3D object (and a little fitting with a material UV editor), your devastated alien planet can have an intricate barren ground that extends for miles, you can populate shelves with scores of identical items, in short, you can work quicker and better with a seamless tiling texture as a background.

Here’s a concept: a retailer wants a photorealistic render of a promotion for Hallowe21en, a ghost surrounded by mountains of candy. In a modeling program, you could perform instancing on a single model of a piece of candy to create large volumes, but it’s a time-intensive solution compared to the relative ease of image-mapping a texture image. In Figure 13, two seed images are used: a main image of some carefully choreographed candy, and a single alpha-masked piece of taffy. The taffy photograph was edited in Photoshop and saved as a PNG, and it’s used to emphasize certain areas of the texture and to break up any static regions of the rendered texture. The procedure is to stamp manually defined chunks from the group photo, and then switch to the taffy seed image, use the entire image as a chunk, and then stamp it into unoccupied areas of the Output texture. It’s a simple, clean solution, made that much simpler because imageSynth reads the alpha transparency in the PNG image.


The finished texture would look better when mapped to a mound if it had a corresponding bump or displacement map. You can hand-paint a displacement map in Photoshop if you just remember that white usually indicated a distance away from the model’s surface while black travels the texture toward the model. You create a new layer on top of the imageSynth texture, and paint to the corresponding areas of the texture, then save the layer to a new file.

In Figure 14, you can see a detailed close-up of an amorphous blob that’s on its way to becoming a 3D mound of candy. The illusion holds up well even at this close-up range and the finished render will not show the mapped texture nearly this closely, so it’s basically good to go.


Here’s the final render. Clearly, imageSynth shortens the production length for many design needs, both in the 2D and 3D world. We feel that the feedback you’ll get as you work on a texture will also trigger some new ideas for future work, some of which you haven’t thought up yet.

Creative software tends to produce this perk!


(c) 2008 Luxology LLC. All rights reserved.

imageSynth contains technology licensed from Allegorithmic SAS.

Visit www.luxology.com

†Adobe® Photoshop® is a Registered Trademark of Adobe Systems Incorporated.


http://www.luxology.com/

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