Windows 95 supported image thumbnailing in Explorer

[linuxlove]

We all know that Windows has supported thumbnail images in Explorer for quite some time now. It's a very handy feature, but did you know that it was in Windows as early as Windows 95? Being that old, it only supported bitmap (BMP) images, yet it did the exact same thing as Windows does today.

Now, how do you activate this feature and what does it look like? To activate it, point the Registry Editor to

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HKEY_CLASSES_ROOT\Paint.Picture\DefaultIcon

Change the (Default) value from

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C:\WINDOWS\SYSTEM\cool.dll,41

to

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%1

Restart the computer. Once Windows 95 is back up, go find some bitmap images and see the thumbnailing.

Before:


After:

Not only does it thumbnail small 16x16px bitmaps, it also thumbnails desktop size bitmap images as well, which can be seen in before.bmp, moon.bmp and untitled.bmp.

So there you have it, an interesting bit of old Windows trivia. I don't know how well known this trick was, but I do know that it was published in Alan Simpson's Windows 95 Bible.

[DeFacto]

Thanks for the tip...

[hogsy]

I wonder why they didn't have that enabled by default...

[linuxlove]

Probably because it's a bit hardware-intensive to scale bitmap images into an icon size. It does cause my 486 to run a tad slower while Windows is scaling bitmap images to icon size.

[hounsell]

Strictly speaking, it's not thumbnailing, it's just setting the icon for bitmaps to the bitmap itself - which works purely because the icon format and the bitmap format are near-enough identical.

Of course, the performance will hurt because it's redrawing that entire bitmap from memory each refresh - something that would have been quite noticeable on the hardware of the time.

Thumbnailing in modern Windows actually generates a thumbnail and caches it.

[WinPC]

Well, I've seen this feature before in TweakUI, upon installing it on a former primary system of mine some years back.

Also, on the same system, I remember creating my own .ICO files using Microsoft Paint, and setting the size for the image itself to be about the same for that of most icons, by first saving them in .BMP format, and then later renaming the extensions from .BMP to .ICO.

[xpclient]

Yes this was one of the popular tweaks on Windows back then so bitmap image icons would be replaced by actual previews. Windows 95 and later also support what is called as an "icon handler" which allows writing a shell extension to extract the preview from any format you support and show it as an icon preview in Explorer. After IE4/Windows Desktop Update is installed on Windows 95, you get the real "thumbnail view" which also shows thumbnails for JPEGs etc. Just write a thumbnail handler (IExtractImage interface) and you can show thumbnails for the format you want. XP introduced thumbnail caching, filmstrip view, thumbnails for folders. Windows Vista introduced a newer IThumbnailProvider interface that also shows thumbnails in the Details pane.

One thing good about XP's thumbnail caching was because the Thumbs.db was stored along with the image files in the same folder, you didn't have to regenerate thumbnails every time you reinstalled Windows. With Vista/Windows 7, a central thumbnail cache is used but not only it often corrupts itself but I am not sure if it can be backed up and restored. Plus, there was a "Refresh thumbnail" context menu command in XP to force refreshing the thumbnail which is also missing.