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How much virtual memory do I need?

We recommend a minimum of 128Mb of virtual memory on your system, or 2 x physical memory for systems with more than 64Mb. If you're going to work with very large images, you may need to increase it even more. However, access to such very large images without enough physical memory will be quite slow.

To check the amount of physical memory on your system:

Right-click My Computer, and select Properties. The General tab shows the amount of physical memory on your system.

If you have plenty of free disk space on your C: drive, you can let Windows manage your virtual memory. However, this does cause the system to run somewhat slower, as Windows has to increase and decrease the swap file size as memory is allocated and released. Other problems with letting Windows manage virtual memory:

  • Once other things make less disk space available on your C: drive, the amount of virtual memory available will decrease.
  • The virtual memory file is much likelier to be fragmented, further reducing VM performance.
  • The virtual memory file will always be on the C: drive. You may want to put it on a different drive or partition to free up space on C:.

To check and set your Virtual Memory settings:

Right-click My Computer and select Properties. From the Performance tab, click Virtual Memory.

  • Let Windows Manage My Virtual Memory Settings This will place the virtual memory file (a.k.a. pagefile or swapfile) on your C: drive, and Windows will increase and decrease its size depending on requirements. While Microsoft recommends this option, it's not the best one for doing lots of graphics work.
  • Let Me Specify My Own Virtual Memory Settings Using this option, you can select the drive and size of the VM file. If you have multiple disk drives on your system, select the fastest drive that has enough free space.

Minimum: 128Mb or 2 x physical memory (or more for large images)
Maximum: same as minimum

By setting the minimum and maximum to the same size, the amount of virtual memory you need or want is always available, and the file is not likely to become as fragmented.

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How do I make a screen shot?

Hold down the ALT button and press the Print Screen button in the upper right hand corner of the keyboard. This will copy to the clipboard a screen shot of the active window. If you want a screen shot of the entire screen, just press the Print Screen button without holding down the ALT button. Once you have copied the screen shot to the clipboard, go into ThumbsPlus and go to Edit | Paste. This will paste the screen shot into a ThumbsPlus view window. In the view window, go to File | Save As to name and save the file.

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What's the best format for storing grayscale or color photographic images?

If you plan to edit, crop or adjust them, we recommend storing in LZW TIFF format. This format is widely supported and provides good compression. Storing with separate color channels sometimes improves the compression ratio, but is not supported by all applications. For compatibility with applications that do not support LZW TIFF, we recommend uncompressed TIFF or PNG.

If your image is in "final form," and you do not intend to edit it further, JPEG is a reasonable option for storage. It offers excellent compression, but there is some loss of image accuracy associated with it. We recommend a quality setting of between 70 and 90.

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What's the best format for storing drawn image files of 256 colors or less?

GIF or TIFF work well for these. TGA, PCX and BMP can also be used; BMP loads the fastest but is not compressed.

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What's the best format for storing bi-level (bi-tonal, monochrome) image files?

We recommend TIFF with CCITT Group 4 compression.

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Why do my GIF files look bad when converted to JPEG?

The JPEG format is designed to compress real-world 24-bit color images. GIF files have already been reduced (usually by dithering) to 256-color (8-bit), so most of the original color information is lost. When they are converted to JPEG, the sharp transitions between neighboring pixels are not handled very well. The Smoothing option in the Save JPEG Options dialog box may improve the situation somewhat.

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When I display JPEG or other 24-bit images, they appear grainy.

ThumbsPlus quickly dithers 24-bit images for display on 8-bit displays. This does not show the true color detail of the original file; you will get much better display results by running a Truecolor (24-bit) or Highcolor (16 bit) display driver, if you can for your display adapter.

Note that you can set JPEG files to load as 8-bit images, using a dithering algorithm in the JPEG library which is better (but a bit slower) than the internal dithering. PhotoCD files may also be dithered to 8-bits while loading. Both of these loading options are available from the Options | File Loading property sheet.

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Why do my JPEG files seem less clear when I edit them and save them many times?

When you are saving as a JPEG, make sure you are not saving the file using the Use Original Quality option or that you are not smoothing the image. When saving the JPEG, you will receive a screen that reads Save JPEG Options. Make sure the Use Original Quality option is not checked and the settings on this screen are 75% Quality and 0% Smoothing. This will give you the smallest, prettiest JPEG image. These settings will now be the default jpg saving options. Note that you can do this in batch also. Just choose jpg as the output format and choose the same settings as above. Click for screen shot

When saving JPEG files, you can select the horizontal and vertical sub-sampling to use for chrominance, from 1:1 (highest quality) to 4:2 (highest compression). The values for loaded files are shown with the quality in the View Window status line.

JPEG format should not be used for "works in progress." Re-saving JPEG files introduces another generation of loss error. We suggest saving your files as TIFFs (LZW-compressed) during interim steps, and only convert to JPEG for external release (i.e., to a Web page).

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What is resolution (DPI)? How does it affect the size of my image files?

Resolution usually specifies how an image was generated; for example, if it was scanned in, the resolution tells how many dots (pixels) per inch (DPI) or dots per centimetre (DPC) were used in the scanning process.

Resolution may also specify a recommended size for output; for example, an image that is 600 by 600 pixels may be specified at 300 DPI to print as 2 inches by 2 inches (600 dots / 300 dpi = 2 inches). Some page layout and word processing programs use the DPI to size a graphic when pasted from the clipboard or loaded from a file.

Regardless of how resolution is obtained, it has no effect on the actual disk size of the file. The disk size depends solely on the dimensions of the image in pixels, the file format, and the compression amount.

ThumbsPlus retains the resolution for file types that support it, and converts to the units for file types it saves in. T+ itself does not use the resolution at all.

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Why do my very large images show as grainy in ThumbsPlus when they show clear in Photoshop or other graphic applications?

If you zoom to actual pixels in Photoshop you will see the same graininess. You are actually seeing the grains in the negative.

In ThumbsPlus, to get the view you desire, go to Options | Viewing | Appearance and check Resample images when reduced. Now go to the Window tab in the same dialog and choose Reduce to window under Initial stretching. Your view will now be as it is in Photoshop.

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