QuickPhoto is an application designed to work with the Connectix QuickCam. It is an improvement over the QuickPICT application as it allows you to save photographs in JPEG format. Additionally QuickPhoto has an automatic exposure feature and a spot-meter which allows you to work efficiently in conditions where the light level is not constant.
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My Growing list of Freeware & Shareware.
I am learning to program my mac efficiently. Such a glorious machine. Below are a few more projects I have completed or am currently working on. Current versions are in brackets. Once released they should be available on Info-Mac archives the world over.
• QuickCamTL - Allows improved timelapse video filming with the QuickCam. Automatic exposure option. (0.3a)
This is wonderful for filming flowers opening, clouds moving e.t.c.
• Crypt - A freeware modeless DA which performs encryption/decryption on the desk scrap. (0.5 (released))
• SecretDiary - An encrypting editor which allows you to keep a secret diary. (0.2a)
QuickPhoto Description
QuickPhoto has two main windows, the Viewfinder window and the Info window. The Viewfinder is just that. It contains the current view of the camera. If a photo has been taken but not saved, then the viewfinder contains that photo so you can gawk at it and decide whether you'd like to save it.
The info window floats around the desktop filled with useful info. Please email me any suggestions on further info needed here. It contains the currrent brightness averaged over the spot meter (see below). The current exposure time in milliseconds and the number of bytes per frame. Play with the compression settings (Video menu) and see how this number varies with different compressors. This is an upper limit on the size of images. The lossless algorithms like JPEG usually produce an image much smaller than this. This means that the actual image file sizes are far smaller that this value. I find for the QuickCam images that the final JPEG image is 5 times smaller than the maximum shown in the info window.
Thaking a Photo
To take a photo with QuickPhoto, simply plug in your QuickCam and makesure it is operating correctly. Then follow the following simple instructions
• Run QuickPhoto and you should see the object of interest (whatever the Camera is pointing at) in the Viewfinder window. Superimposed over the image is a rectangle filled with a grid of black points (121 of them). This is the spot meter used to control the exposure of the camera.
• Choose 'take photo' P from the Photo menu. The viewfinder now displays the Image.
• Choose 'save' or 'discard' from the File menu. The photo will be saved in JPEG format and you will be prompted for the filename. The photo is also put on the desk scrap in uncompressed PICT format so you can paste it into any applications of your choice.
Exposure Control
In the Set Exposure menu option there are two parameters which can be set. The first is the desired brightness, specified in percent. One hundred percent means that the average value of the pixels in the spot meter is saturated (i.e., white/ slow exposure time) and zero percent means the pixels being black (fast exposure time). You probably will not want to change this value outside the range 40-60 %. QuickPhoto uses a simple algorithm to adjust the exposure time of the QuickCam in such a way as to make the brightness inside the spot meter (see below) is close to the desired brightness. The default value for this parameter is 50%.
The second parameter which can be set from the 'Set Exposure' menu option, is the shutter delay. This is the number of seconds which QuickPhoto will wait (after the 'Take Photo' command is issued) before taking the photo. The default setting here is zero, meaning that the photo is taken immediately.
Spot Meter
The spot meter is a rectangle that you define in the video window. This rectange defines the are over which the automatic exposure is controlled. For example if the rectange is a small square, then QCTL checks to contents of that square and adjusts the exposure so that the contents of that square have an average brightness equal to that specified in the exposure dialog.
The rectangle you define must be a multiple of eleven pixels high and wide. To precisely position this rectangle it is best to click on the top left corner first and then drag (holding the mouse button down) to the bottom right corner. Try doing it the other way to see why. This shouldnt be a problem unless your spt rectangle is miniscule. Something I don't recomment as then the brightness of the backgroun can appear to fluctuate dramatically as the light intensity varies inside the spot meter rectangle.
Compression
The compression menu item (Video Menu) pops up a standard dialog which allows the user to set the compression type for their photo. The default is JPEG and the output is then a JPEG standard still image. If one chooses NONE for the compression then the output is a raw binary (4 bits per pixel) dump of the camera image.
KNOWN BUGS & FEATURES TO COME
• Will allow the user to save the image in a QuickTime PICT 2 format.
• Will write the estimated JPEG image size to the info window.
