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Create an online art gallery using Satori (Part 2)

Create an online art gallery using Satori (Part 2) - Mark Graham looks at a technique to help you scan A3 images on an A4 scanner and then stitch them together using Satori image editing software.

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A tutorial for all versions of Satori (2.29 and above) by Mark Graham
All images reproduced by kind permission of Toby Barclay

1) The story so far...
My friend, having inherited a number of prints (etchings) by the artist Nathaniel Sparks, wanted to create an online gallery http://www.natsparks.co.uk where he could display them and hopefully sell a few. He also wanted to be able to supply, on CD-ROM, a high-resolution version of the gallery.

In part one of this step-by-step (April issue) we scanned the images in sections, photostitched and then saved them. Now we're ready to tidy them up with Colour Correction, Crop and Web Optimization tools.

Let's begin by starting Satori and loading the file we're working on. If you've completed Part One of this tutorial in the April 2001 Techniques section you can load the bitmap you saved at the end of your session - Abbey1.jpg or click here to download it.

From the Satori File menu click Open. This will launch the Load Image dialog. Locate the file and click Open. The image will be opened into a new window on the desktop.

2) Colour Correction
This image is too dark. Let's lighten it and increase the contrast...

Click the Layer button on the Actions Palette to display the Layer controls. By default the contents of the Operations tab will be displayed. Click the Color Correction button.

Pressing Color Correction launches the display of a group of controls arranged in two tabs on a modal, floating dialog. By default, the contents of the Slider tab are displayed. Satori provides two methods for color correction; the Slider method that allows setting for luma and color balance and the Curve method that allows individual color channels or all channels at once to have their tonal quality boosted or reduced, over the entire range of colors.Use the sliders in the Luma panel to change the Brightness or Contrast of the image. Moving the slider to the right will increase the parameter, whilst moving to the left will decrease it.

The same ease of use applies to the Color Balance sliders. For example, moving the Cyan-Red slider towards the red end will increase the amount of red in the image, at the expense of cyan.

At the end of each slider movement the current view will preview the effect of the current settings. Reset All Sliders cancels all changes and resets the sliders to zero - use this if you want to start over.

For the image of Westminster Abbey which is (mostly) monochromatic we will use the Brightness and Contrast controls on the Slider tab. Set a Brightness value of around 20% and set the Contrast slider to 30%. Press Apply when you are satisfied with the preview. A color correction object will now be applied to the layer using the current settings.

3) Crop
The image was constructed (in Part One) by combining 2 partial scans - there is material at the edges this is not required and we can remove this using the Crop tools. This is a group of four text buttons that handle the cropping of canvas files, located in a panel labelled Crop Region, and which are accessed by clicking the Canvas button on the main Actions Palette.

Define Crop changes the cursor to a crop cursor to prompt you to define a rectangle inside the image window that will become the Crop Region. By definition a Crop Region is smaller in size than the canvas from which it was defined. At the completion of a Crop Region definition a new, Crop Area window is opened and the Display Crop and Reset Crop text buttons become enabled. The pixel co-ordinates of the Crop View are displayed in the window title.

At this point, version 2 users should Save their work by clicking Save As from the File menu and proceed to Step 5 below.

4) Web Optimising
Version 3 users can take advantage of Satori's Web Optimization tools. The Web Optimizer Wizard generates files with an optimum balance of file size versus image quality for use on websites and other Internet applications.   

Selecting Optimizer Wizard launches the Image Optimizer dialog.

The left side of the dialog contains three panels that contain tools for setting JPEG Compression options, 256 Color Paletted Format options and Image Dimensions. Clicking the JPEG button enables JPEG Compression. The compression value (0-100) is set using the value spinner or by typing in the value field. As you change the compression value, the result is displayed in the preview window. Selecting this mode deselects the 256 Color Paletted Format mode.

The Progressive checkbox selects a JPEG format that can be displayed during loading, progressively increasing the quality of the image as the load proceeds. In general Progressive files are slightly smaller.

The tools in the Variable Color Paletted Formats panel set the options for .BMP, .GIF, and .PNG compression.

Click on the BMP, GIF and PNG text buttons to select the desired output file format.

Type, or use the pop-up slider, to set a value between 2 and 255 in the Number Of Colors In Palette field - the fewer colors, the smaller the final output file size. As you change the value, the result of the change is displayed in the preview window.

Type, or use the pop-up slider, to set a value between 0 and 100 to determine the level of Dithering that will be applied to the image. As you change the value, the preview updates automatically. Dithering diffuses pixels to increase perceived color range.

Below these is a box, which displays the current color palette, defined in the Use Palette name field. There is Right Button Click menu of options including Add Color, Remove Color and Palette Info.

The Use Palette field contains a list of 8 options that can be selected for BMP, PNG and GIF formats. Grayscale is a palette of 256 or fewer shades of gray. Windows uses the Windows system s default 8-bit color palette, which is based on a uniform sampling of RGB colors. Macintosh uses the Mac OS system s default 8-bit color palette, which is based on a uniform sampling of RGB colors. Black and White is a two-color palette. Browser Safe is a palette of 216 colors common to both Windows and Macintosh computers. This palette is Web 216 compliant. Black Body is a palette that displays the colors of a black object as it is heated. Custom is a palette that has been modified and saved. Adaptive is a custom palette derived from the actual colors in the image. It creates a custom palette by sampling colors from the spectrum appearing most commonly in the image. If the image is predominantly green and blue then the adaptive palette will show this.

Beneath the preview window at the right of the dialog are reported the current File Size, Download Time and At values. Changing the value in the At field changes the corresponding value for the Download Time.

Clicking the Save Now button launches the Save Bitmap As dialog.

5) Saving bitmaps
The base dimensions of the whole image are 1275 x 2755, but since we have defined a Crop Area this is selected by default in the Output Parameters panel and the slightly reduced dimensions are displayed in the X and Y fields.

To save out a high resolution version suitable for use on a CD we can accept all the default settings and simply type a filename such as Abbey.jpg and click OK. However for use on a website we'll need a much smaller (lower resolution) version. To do this, type a value of 640 in the Y Dimension field (this will cause the value in the X Dimension field to reduce pro rata) and click OK. This will launch the Save Jpeg Options dialog.

It's a matter of preference (of course) as to how much compression you finally decide to use - in my experience a value of 80% usually provides an excellent compromise between image quality and download time. Our final image (below) comes out at 39KB.

This process was repeated with each of the scanned images and the final results may be viewed by visiting the Nathaniel Sparks Gallery at http://www.natsparks.co.uk

Satori PhotoXL v2.29 is fully-enabled Freeware and is available from  http://www.satoripaint.com

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