Tag: photography

Entries for tag "photography", ordered from most recent. Entry count: 5.

Warning! Some information on this page is older than 6 years now. I keep it for reference, but it probably doesn't reflect my current knowledge and beliefs.

Pages: 1

# What is Samsung phone doing to photos?! (sharpening a lot)

Sep 2017

I now use Samsung Galaxy S7 smartphone and I'm quite happy with it, except for the camera. I noticed that all the photos taken with it look bad. There is clearly something wrong with them. When I zoomed in, I noticed that the device applies insane amount of sharpening. Every photo looks like it was first filtered by bilateral filter (a kind of edge-preserving blur that is used for noise reduction) and then sharpening with intensity set to maximum, which causes annoying ringing artifacts around the edges.

I decided to make an experiment. I gathered all the devices I had access to that can take photos and I brought them to a place where I could photograph a building that has many sharp edges, plus some tram cables. It was the middle of a sunny day, so lighting brightness and contrast was high and devices didn't have a reason to apply too much processing to the photos taken. I configured all of them to fully automatic mode, maximum resolution and JPEG as output format (except Canon camera, where I forgot about it, so I actually made CR2 RAW that I later converted to JPEG). Devices I used for comparison were (click on each link to access original photo file):

When you zoom in to the building, you can clearly see that both Samsung phones applied very strong sharpening. It turns out this is a known problem. There is a discussion on Reddit, as well as YouTube video about it. Sony phone and DSLR don't have this effect.

Samsung Galaxy S6:

Samsung Galaxy S7:

Sony Xperia Z2:

Canon PowerShot G7X Mark II:

Nikon D90:

What's interesting is that the Canon camera also applied some sharpening, and did it even in RAW! (How can they call it RAW then?!) Fortunately in this camera it can be disabled: While in photo shooting mode, press MENU button, go to tab 6, select "Picture Style" and set it to "Neutral", so that the first parameter in the sequence of numbers (meaning "Sharpness Strength") is 0.

In Samsung phones this filter cannot be disabled :( The only way to take pictures without it is to use RAW, where it's not applied. To do it, while in photo shooting mode: swipe left, choose "Professional", enter configuration, select "Image size" and there enable "Save RAW and JPEG files". You need to enter "Professional" mode every time you want to take a photo. Then of course you need to process the image on your PC and convert it to JPEG, e.g. in Adobe Lightroom or other similar program, but there you can decide how much sharpening do you need (or none).

Comments | #photography #hardware Share

# Color Temperature of Your Lighting

Oct 2016

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.

Comments | #graphics #photography #video Share

# Making Tilt-Shift Photo in GIMP

Jul 2014

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.

Gdańsk Tilt-Shift

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:

  1. Choose a photo of a city panorama. Open it in GIMP.
  2. Use Crop Tool to crop it so no horizon line or sky is visible, only ground.
  3. In Layers panel, click appropriate button to duplicate layer.
  4. Make sure the top layer ("copy") is selected. Select Filters > Blur > Focus Blur. Change radius to some higher value (I used something around 10-16 for image in Full HD resolution). Confirm with OK.
  5. Now right-click on the top layer and select Add Layer Mask. Mask is created for this layer and selected so now drawing will change layer transparency instead of color.
  6. Select Blend Tool (the one for drawing gradients).
  7. In Tool Options panel, select gradient "FG to BG (RGB)" and change Shape to Bi-linear. Make sure current colors are: foreground = black, background = white.
  8. Draw the gradient by pressing left mouse button in the center of the image, dragging cursor to the top or bottom (hold Ctrl to draw perfect vertical line) and releasing it there.

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:

  1. Flatten image by right-clicking on top layer and selecting Merge Down.
  2. Enhance colors. You can, for example, increase saturation and contrast.
  3. Export image with File > Export As.

Comments | #photography Share

# Infrared Photography

Jun 2012

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.

Comments | #infrared #photography #optics Share

# Unofficial Firmware for Canon PowerShot A610

Apr 2011

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:

Comments | #photography #hardware Share

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