25

A well know technique is called "luminosity masks". You create a selection mask where the pixels selection level is: 100% or near 100% in the luminosity range that you want to change, 0% or very low in the luminosity range you don't want to change, intermediate for pixels between these two ranges This done by: making a grayscale copy of your image ...


23

Other users gave great answers about tuning your computer. However since you mentioned costco, this is a costco specific answer: I've sent many prints to costco and had great luck. However not so much, before I realized that they were "auto correcting" images. One batch of birth announcements I had to send three times because the color was "off" no matter ...


15

Inherently, no. The RGB model is natural for recording light, and the CMYK model is natural for printing (where reflected light is subtracted). But see Are RGB numeric values equal to CMYK percentages? — the loss in conversation isn't inherently because RGB to CMYK is inherently lossy, but because the actual color spaces of the devices used are different, ...


14

The color correction is acting as expected. The point of using a color target is to adjust for the color of light to assume that the light is white. If you want to have the color that is present when shooting, you should instead use a fixed white point that you consider to be standard white, but naturally people's eyes will adjust quite a bit for the color ...


11

The tool displaycal-profile-info, part of the DisplayCAL package, can do this. This works (and works basically the same way) for Windows, Mac, and Linux. See for example for my (calibrated) ThinkPad screen: ... which has a 60% coverage of sRGB and 43% coverage of Adobe RGB.


10

Camera Colorimeter is an app on Google Play which uses the camera on your phone as a colorimeter for calibrating other devices. https://play.google.com/store/apps/details?id=com.auralisoft.colorimeter [Some experimental results] I get very consistent capture results using the back camera on a Nexus 6. The following are 10 captured RGB values of the same (...


10

You can use imagemagick's identify program for this. Example: $ identify -verbose example.jpg | grep -A1 Profile-icc Profile-icc: 560 bytes Adobe RGB (1998) (I could not get this out with the exiv2 tool mentioned in another answer.)


10

from Charles Poynton "The rehabilitation of gamma": Misconception: The nonlinearity of a CRT monitor is a defect that needs to be corrected. Fact: The nonlinearity of a CRT is very nearly the inverse of the lightness sensitivity of human vision. The nonlinearity causes a CRT’s response to be roughly perceptually uniform. Far from being a defect, ...


10

I am a former broadcast engineer, and I currently work in feature films and television as an editor and VFX supervisor. Many statements on here are incorrect. Gamma in the signal path is a desired benefit, and a design choice by early video engineers to reduce perceived noise in transmission. All vacuum tubes, CRTs included, exhibit various non-linearities ...


10

I'll interpret your question in the opposite way everyone else has. You seem to me to be asking how to prevent the details becoming visible again. Once you have darkened your image, increase the black point. This will make the new shadows actually black, and prevent the details from being recovered. You can do this in levels in most editors, or with curves: ...


9

Hopefully someone more knowledgeable than me will complete my response. The little I know about these curves follows: 1) Characteristic Curves: The more a negative is exposed, the darker it gets. The log-log density/exposure curves simply show how dark the film gets in response to more exposure. These lines do not coincide on color negatives, because of ...


9

I think it was the EktaSpace that was invented to hold all colors of films. Since silver halide color papers are still used as media for printing from digital, there are also color profiles of photographic papers floating around the Internet. See https://www.drycreekphoto.com/icc/ for examples. These should give you some idea. As you can imagine, ...


9

The first thing you must realize is that what you are seeing on your monitor is not "the" raw file. What you are seeing is an 8-bit demosaiced preview conversion of the raw file created by Photoshop (or whatever other raw conversion application you are using) based on the current settings. It's just one of many possible interpretations of the full ...


8

Yes - you need to calibrate your monitor. One option, which is what I did, is to buy a relatively cheap colorimeter, at the time the Huey Pro was generally available. I used it as a travel colorimeter. Later, when I wasn't traveling as much, I bought a more expensive colorimeter (Lacie Blue-Eye Pro) for my home IPS monitor. I found that the cheaper ...


8

TLDR: Choose a print shop that provides ICC profiles. Soft proofing is an important step for optimal results. If a shop doesn't share its profiles there are two reasons that come to my mind: lack of knowledge (very bad), or different printer types for the same printing product, meaning multiple orders could give different results even with the same ...


8

After further research, here is a partial answer taking as source Blog-Couleur: Quelles sont les valeurs RVB de la colorchecker ? and BabelColor PDF and the Xrite website. The last row seems to be white 95%, neutral 80%, neutral 65%, neutral 50%, neutral 35%, black 20%. On trouve entre le blanc et le noir, une série de 4 gris : neutral 0.35, neutral 0.50,...


8

According to ICC color correction in Firefox, Firefox has been capable of reading colour profiles in images since Firefox version 3 (released 17 June, 2008). This was configurable, and initially defaulted to 'off', but this default behaviour was changed to 'on' in Firefox 3.5 (released 30 June, 2009). However, this comes with a big caveat. It seems ICC ...


7

If the image is accurate for color there can be a few things going on here. None easy to fix. As I had mentioned in an earlier answer about LED display technology, this is more than likely a metameric match produced my your measurement device from the narrow band LED backlight. The problem with LED backlights (or any backlight for that matter) is that ...


7

You would convert the image to the sRGB color profile. This profile is indended to match the color capabilities of a monitor. This is commonly used for images that are used in web pages, and for example offered as an option when exporting images for web in Photoshop. By converting the image to sRGB the color profile can be omitted from the file, which ...


7

Consider this example from Cambridge in Colour: By applying gamma encoding, we are able to represent the original image more accurately, with the same bit depth (5, in this example). This is achieved by using the 32 levels in a way that more closely corresponds to the human eye. In other words, it's a form of compression. JPEGs, for example, can actually ...


7

Carol, are you sure you have the U2414M? That's Dell's medium gamut variant of the monitor, covering about 75% of Adobe RGB. So I think that if that's the monitor you have, it's behaving as expected. See this review on TFT central for details. Dell's terminology here is unfortunately confusing, since previously the U2413 (with no M) was the wide-gamut ...


7

I asked Dan to answer your questions. Here is what he wrote: "Anything prepared with color fidelity in mind is best viewed in a graphic arts viewing booth or, if none is available, sunlight or equivalent. That said, one shouldn't take a product printed on an offset press too seriously as there will be unavoidable slight variation between copies. The poster ...


7

It simply isn't possible for any print, which only absorbs light, to produce a colorimetrically accurate and useful reproduction of the CIEXY human gamut "horseshoe." The curved boundary represents the maximum color saturation. It is the result of a single wavelength of light between about 400nm to 700m. Along the bottom line of the horseshoe, the position ...


6

The camera sensor does not have a color space that allows going back and forth to XYZ since it does not have the same sensitivity curves as the human eye (Luther - Ives condition). The best that can be done is come up with a transform matrix that minimizes the sum of the errors in LAB for the set of standard colors (Gretab -Macbeth). I believe this process ...


6

Users have identified the problem as faulty sensors however the problem is not faulty sensors but rather faulty filters. It appears that poor quality control has resulted in residue in the filters which causes them to become opaque. The solution is not too difficult but is a little tricky. The fix requires disassembling the device and cleaning the crud off ...


6

Hope this helps - Asked my Canon Rep as I was also interested and this is what he sent me; The ICC profiles installed for your printer and Canon photo paper appear as follows. CANON - PRINTER MODEL < PAPER TYPE> PRINT QUALITY (For example: Canon Pro9000 PR1) (1) Printer model name (2) Media type Each letter pair represents its respective Media ...


6

Performing the operation directly using the chromaticity coordinates (ie: taking the midpoint between the two chromaticity coordinates) will yield incorrect results as the chromaticity diagram is highly non uniform. Assuming you are using linear light values you could perform the following chain of computations: CIE xy to CIE xyY (Optional) for each pair ...


6

I foud this graphic on photo.net, in a thread discussing the same topic: I can't vouch for its veracity, but it looks reasonable. Both of the depicted films are a bit wider than AdobeRGB in the reds, but much shorter in green. But see the discussion on the next page, deeply saturatd greens require high densities and thus dark colours, which this chart doesn'...


6

The standard gray card is 18% gray. Take a sample gray card with you to the paint store and have them custom mix. The reflection readings are: 0.75 red 0.75 green 0.75 blue 0.75 via the yellow visual filter. These values are the reflection densities of the gray card.


6

A Color Gamut refers to colors within a Color Space which is a representation of which colors exist within it and which ones are not. It does not usually define a representation which is why there is not specific number of colord within it. sRGB for example use 3 chromacities which form a triangle within all possible colors. When one uses an 8-bit-per-...


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