186

There is a tool called dcraw which reads various RAW file types and extracts pixel data from them — it's actually the original code at the very bottom of a lot of open source and even commercial RAW conversion software. I have a RAW file from my camera, and I've used dcraw in a mode which tells it to create an image using literal, unscaled 16-bit values ...


43

I will only answer the first question: What are frequencies in images? Fourier Transform is a mathematical technique where the same image information is represented not for each pixel separately but rather for each frequency. Think about it this way. The sea has waves some of which are very slow moving (like tides), others are medium in size and still some ...


29

Exposure fusion is a process that takes multiple images and combines them to create a single image while only keeping the properly exposed elements. In contrast to HDR images, exposure fusion is more basic, gives a more realistic effect, and requires fewer steps. The exposure fusion(fusion, or EF) process takes each individual pixel and assigns a weight to ...


24

Luna 3 did something as complicated as you thought: It took photos on a film, processed it in a kind of onboard minilab, and then scanned and radioed it back home in analog way not unlike an old fax. Funniest part was that Soviets didn't have the technology of radiation-hardened film, but Americans did. They used it against Soviets in high-altitude spy ...


22

Check out Fro Knows Photo. There is a weekly RAW file you can edit and you can post your result on the forums (they are at edit 81 at the time of writing). Jared (the guy behind the site) then selects a handfull RAW edits from the forum and comments on them in a youtube video. As a plus, Jared and/or Adam will give a full tutorial (again youtube video) on ...


20

To reduce the processing time for long exposures, you want to turn off Long Exposure Noise Reduction. However, you may not want to give up the benefit of LENR. Long Exposure Noise Reduction (LENR) is Canon's nomenclature for in-camera dark frame subtraction. When you take a photo the camera will expose the image normally and then use the same settings to ...


19

I think the main problem is one of dynamic range, your algorithm is probably right but you're working on the wrong type of data. A point lightsource that would otherwise clip and go pure white gets spread over a larger area by a defocussed lens, so that it forms a disc that isn't as bright and therefore doesn't clip. That's why you get those nice circles ...


19

Amongst the myriad online pages documenting the Viking series, here's one which states clearly The Viking Lander camera design was very different from vidicon framing or CCD array cameras. The lander camera was a facsimile camera with a single, stationary photosensor array (PSA), and azimuth and elevation scanning mechanisms. A lander image was ...


19

It's been done in X-rays. The TimePix is a 256x256 detector. It has three operating modes: the usual "total energy in this pixel since we started integrating"; Time-over-Threshold (TOT): the detected pulse height is recorded in the pixel counter in the TOT mode; and Time-of-Arrival (TOA): the TOA mode measures time between trigger and arrival of the ...


18

You are missing some obvious problems with this idea. You want to "continously" capture the light data, but that's already being done. Apparently you mean to have a series of images available after the exposure, each exposed from the start to times advancing withing the whole exposure. The later images would have more detail in shadow areas, but might ...


16

IP-Slicer perl script can create slices which can stuck together into a ball. You can define the number of slices. The following command will create 12 slices, where the sphere circumference is 1500 pixels. sphere-slicer.pl 12 1500 sampleimage.jpg Sample input: Output (12 images):


15

The simple recipe is to convolve with a Laplacian of Gaussian kernel (3x3, with 8 in the middle surrounded by -1 and take the abs(result)) . After this you get some artifacts if it is a jpeg image, and out of focus borders that have a high intensity difference will also "ping". The result you can threshold to detect the strongest edges and remove teh ...


13

All image processing packages should make this easy. I'll show you how to do it in Mathematica, if you have access to this system. Mathematica is a programming language, but it's really easy to do these kinds of manipulations, so if you have access to it (e.g. through a university site license), I recommend you give it a go! First, import the image: img =...


12

There's nothing wrong with your settings. On my monitor the clouds look fine, not blown out and the greens are nice and saturated. The most likely explanation is that your laptop screen is inferior i.e. it can't display the same range of colours or the same contrast as your desktop. In addition to that it's not calibrated either. You don't have to buy ...


12

Aliasing is the result of repeating patterns of roughly the same frequency interfering with each other in an undesirable manner. In the case of photography, the higher frequencies of the image projected by the lens onto the sensor creates and interference pattern (moiré in this case) with the pixel grid. This interference only occurs when those frequencies ...


12

First of all, in optics, only light adds up and darkness does not. Make sure that your algorithm does not bleed dark pixels outwards their original location. Resulting pixels should rather resemble maximum of nearby source pixels than average. Or, to be even more exact, you'd be summing up logarithms of affecting source pixels. Another possible cause why ...


11

You can probably do this by creating an action and then batch processing: Create the action with an open file in photoshop start recording do File > Save As > and set file type to PNG or use File > Save for Web if you need to resize or make other modifications click Save stop recording and save action as "Save As PNG" (there may also be some built in ...


11

The physics simply doesn't work that way. Aliasing irreversibly transforms frequencies past the Nyquist limit to appear as frequencies below the limit, although those "aliases" aren't really there. No amount of processing a aliased signal can recover the original signal in the general case. The fancy mathematical explanations are rather long to get into ...


11

I don't know if it's the easiest but this works pretty well for my needs: $ align_image_stack -a aligned -C *.jpg 'align_image_stack' utility is part of hugin, and under Debian/Ubuntu (and other derivatives probably) you acquire it by installing 'hugin-tools' package. In the command above: '-a aligned' sets prefix of the name of output images to 'aligned' ...


11

Support for reading HEIF was added to ImageMagick 7.0.7-22, you have to install it with --with-libheif flag. e.g. on macOS with Homebrew: brew install imagemagick --with-libheif. If you have previously installed imagemagick with Homebrew, you need to uninstall it by brew uninstall imagemagick first. One other option to convert HEIF → JPG on macOS is by ...


11

You suggest "Or every time a photon hits a pixel on the sensor give it a timestamp" — this would be a huge amount of data. A quick search suggests that each pixel — or sensel — in a digital camera saturates at somewhere between 20,000 and 100,000 photons. Let's say that we're happy with a 12 megapixel camera and are okay with the lower side of sensitivity ...


11

It's a really really big grid of numbers. Everything else is processing.


10

Color photography is indeed based on the tri-color theory. The world saw the first color picture in 1861 made using red, green, and blue filters by James Clark Maxwell. Today’s color photography is based on his method. In 1891, Gabriel Lippmann demonstrated full color images using a single sheet of black & white film, no filters, no colored dye or ...


9

From a technical standpoint, "saturation" is the extent of chromaticity for a certain hue...the hue's "colorfulness". Technically speaking, pink would be a less colorful magenta, but roughly the same hue, where as red would be a distinct and colorful hue on its own. You might think of light rose or salmon to be less colorful variations of red. When it comes ...


9

Lightroom offers primarily integration and simplicity. This means a highly integrated workflow which takes care of images from import to publication and a feature set designed to cover the most common processing tasks for photographers. In terms of processing features, Lightroom is far less capable than Photoshop and even includes a workflow to process ...


9

Have a DOG sniff out blur in the photos. If you're going to be penalizing for digitally enlarged photos, you might as well penalize for out-of-focus photos too. The blurred edges and details in both cause the same bad experience for viewers, regardless of whether it is caused by a small original or poor focus. What you want to do is detect blur, which is an ...


9

There doesn't appear to be any moire in the image itself. What you are seeing are scaling errors when the image is resized by a particular application for display on a particular size screen or print. To solve this you can create, optimize, and export different resolutions of the image for different display environments. For instance the display on a ...


9

For photographic images and when a not too high level of compression is used, the loss of quality in the JPEG format is negligible and invisible. You'll pretty much only be able to notice it by directly comparing individual pixels around sharp edges or in very smooth color gradients. This is why JPEG is so popular. If it always resulted in noticeable loss ...


9

The 14 bit depth is the limit of the physical sensors capabilities, it isn't just that the engineers decided to throw away useful data. An increasing number of bits available in a sensor reflects an increasingly larger complexity of circuitry and precision needed to resolve those progressively finer and finer details. Complexity and precision don't come ...


9

This is actually really simple: your image is shown in color by Darktable because it renders the preview from the RAW file in order to show it to you — including demosaicing. (Or, depending on settings, it may initially show you a low-quality JPEG preview actually embedded in the RAW file by the camera.) This is why I find the whole "RAW isn't an image; it'...


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