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Entries for tag "photography", ordered from most recent. Entry count: 4.
Color Temperature of Your Lighting
In photography, video and all graphics in general there are so much more parameters to consider than just exposure, meaning lighter or darker image. One of them is color temperature, or white balance. It's about what we consider "white" - a frame of reference, especially concerning light source and so all the objects lit by it. It's not real temperature, but we measure it in Kelvins. Paradoxically, lower color temperature values (like 3000K) mean colors that we call "warmer" - more towards yellow, orange or red. Higher temeratures (like 7000K) mean "cooler" colors - more towards blue. Values like 6500K are considered equivalent of a sunlight during the day, while light bulbs usually have around 3000K. Color temperature of your lighting is important when you work with colors on a computer. They recommend to use 6500K light source for that purpose.
I decided to make an experiment. Below you can see photos of part of my room, with a test screen displayed on my monitor, piece of my wall (behind it, supposed to be white) and a piece of furniture (the right part, also should be white). The monitor is LG 23MA73D-PZ, with IPS panel, calibrated to what I believe should be around 6500K (setting Colour Temperature = Warm2).
Left column shows a photo taken in the middle of the night, with lighting by LED lamps having 3000K color temperature. Middle column is the same scene lit by different LED lamps having 6500K. Finally, right column show a photo taken during the day, using only sunlight.
The only remainig variable is white balance of the photo itself. That's why I introduced two rows. Top row show all three photos calibrated to same white balance = 6500K. As you can see, the image on the screen looks pretty much the same on all of them, because monitor emits its own light. But the wall and the furniture, lit by a specific light source, seems orange or reddish on the first photo, while on the other photos it's more or less gray.
Our eyes, as well as cameras can adjust to changing color temperature to compensate for it and make everything looking neutral-white again. So the second row shows same photos calibrated to white balance of the specific light source. Now the wall and the furniture looks neutral gray on all of them, but notice what happened with the image on the screen when light was 3000K - it completely changed colors of the picture, making everything looking blue.
That's why it's so important to consider color temperature of your light sources when working with color correction and grading of photos, videos or some other graphics. Otherwise you can produce an image that looked good at the time of making, but turns out to have some color cast when seen under different lighting conditions. Of course, if you just work with text or code, it doesn't matter that much. It is more important then to just have a pleasant lighting that doesn't cause eye strain, which would probably be something more like the 3000K lamps.
Making Tilt-Shift Photo in GIMP
There is an interesting photographic effect called Tilt-Shift. It makes a photo of city panorama looking like a miniature due to small depth of field. Wikipedia says it can be obtained optically with some advanced techniques, but it can also be approximated with postprocessing.
Yesterday I visited St. Dominic's Fair in Gdańsk, where I had an opportunity to enter a Ferris wheel and take a photo of my city from some height. Here is my experiment with tilt-shift. I've made it GIMP.
To do it, top and bottom of the photo needs to be blurred. But an out of focus photo is not the same thing as standard Gaussian blur. That's why a special kind of blur is needed. There is a GIMP plugin for it: Focus Blur (Windows binary can be found HERE). In Photoshop, the effect is available as Lens Blur.
Image needs to be blurred more the closer a pixel is to the top or bottom edge of the image. But I have no idea how to do blur (or any other effect) with intensity varying over image location, so here is the trick: We can use only two layers - normal and heavily blurred - and blend between them using layer mask.
So to add tilt-shift effect to your photo using GIMP:
If you've done everything right, you should now already have blending between layers applied so that top and bottom of the image looks like out of focus. Now you can:
I'd like to share results of my first experiments with infrared photography. Infrared is the frequency of light invisible to human eyes. Cameras also shouldn't register it, so manufacturers put special filters to block these frequencies. Some of them are better, some are worse - the latter make a camera better candidate for IR photohraphy.
To take an infrared photo, one needs a special filter (see this category on Allegro.pl). Such filter blocks all visible light, so it looks totally opaque black. When using it, only infrared light enters the camera. Some additional issues:
After transferring a photo straight from the camera, it looks totally red.
But after correcting while balance in some application, it turns out that other channels also register some of the IR light, so it's not totally black and white - we can see some colors and achieve interesting effects, especially after applying some additional filters in a graphics program (like Channel Mixer command).
An image registered in infrared has some interesting properties:
You can find more of my infrared photos in gallery: Infrared @ Picasa Web.
Unofficial Firmware for Canon PowerShot A610
I have Canon PowerShow A610 digital camera. Today I've found a unofficial, free, powerful firmware for it, as well as other models from Canon. It's called CHDK - Canon Hacker Development Kit. Installation is quite easy and totally safe - it's enought to put the software onto SD card. On Windows this can be done with CardTricks application. The firmware adds some useful features, like:
I recommend this firmware to anyone who owns a Canon camera. Mine now looks like this: