If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
I am trying to get a true color photograph of an oil painting. Because
of the propensity of the shiny and irregular surface of the painting, reflection has been a problem, requiring some creative lighting set ups. I have several photos taken with different cameras using differnet settings and setups. On my computer screen, they each have slightly diffenet colors. The image will be sent to a printer 3,000 miles away. I would like to be able to ensure that the printed colors are as true as possible to the actual painting. It occurred to me that if I had the exact RGB and/or CMYK numbers for a few spots on the painting, the printer should be able to reproduce it pretty accurately. What's the best way to get the exact RBG or CMYK numbers for the colors on the actual painting? Is there a color wheel I can buy that I can hold up to the painting? Is there some electronic scanner that will show me a readout? |
#2
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
Jennifer Murphy wrote:
I am trying to get a true color photograph of an oil painting. Because of the propensity of the shiny and irregular surface of the painting, reflection has been a problem, requiring some creative lighting set ups. I have several photos taken with different cameras using differnet settings and setups. On my computer screen, they each have slightly diffenet colors. The image will be sent to a printer 3,000 miles away. I would like to be able to ensure that the printed colors are as true as possible to the actual painting. It occurred to me that if I had the exact RGB and/or CMYK numbers for a few spots on the painting, the printer should be able to reproduce it pretty accurately. What's the best way to get the exact RBG or CMYK numbers for the colors on the actual painting? Is there a color wheel I can buy that I can hold up to the painting? Is there some electronic scanner that will show me a readout? Measuring the colours "exactly" will have the same lighting and reflectance issues as your photograph, I'm afraid. You can quite readily calibrate your shot by including a known target in the photograph, or shooting the target under the same conditions as your photograph. Proper targets aren't super-cheap. Here's a handy page about this: http://www.aff.org.au/AFF2_Eckert_co...al_summary.htm BugBear |
#3
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
On Thursday, April 4, 2013 9:48:48 AM UTC+1, bugbear wrote:
Proper targets aren't super-cheap. Here's a handy page about this: http://www.aff.org.au/AFF2_Eckert_co...al_summary.htm BugBear Buy 2 identical targets, have one delivered to you and the other at the point of printing, shot the target next to the painting with the same lighting and same white balance, print the target shot by you and have it compared with the one delivered. DanP |
#4
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
On Thu, 04 Apr 2013 09:48:48 +0100, bugbear
wrote: Jennifer Murphy wrote: I am trying to get a true color photograph of an oil painting. Because of the propensity of the shiny and irregular surface of the painting, reflection has been a problem, requiring some creative lighting set ups. I have several photos taken with different cameras using differnet settings and setups. On my computer screen, they each have slightly diffenet colors. The image will be sent to a printer 3,000 miles away. I would like to be able to ensure that the printed colors are as true as possible to the actual painting. It occurred to me that if I had the exact RGB and/or CMYK numbers for a few spots on the painting, the printer should be able to reproduce it pretty accurately. What's the best way to get the exact RBG or CMYK numbers for the colors on the actual painting? Is there a color wheel I can buy that I can hold up to the painting? Is there some electronic scanner that will show me a readout? Measuring the colours "exactly" will have the same lighting and reflectance issues as your photograph, I'm afraid. Aha. If I shine a red light on it, it will look different than if I shine a green or pure white light on it. So the only way to get the "true" colors of the object is to take it to a carefully controlled environment where it is illuminated by a perfectly balanced light source. This business is maddeningly complex and nuanced. You can quite readily calibrate your shot by including a known target in the photograph, or shooting the target under the same conditions as your photograph. Proper targets aren't super-cheap. Here's a handy page about this: http://www.aff.org.au/AFF2_Eckert_co...al_summary.htm What if I lower my expectations or, at least, make them soemwhat more realitic. Instead of saying I want to get the "exact" RGB numbers, suppose I say that I want to get the RGB numbers for the painting as it looks hanging in my living room under midday ambient light? Could I then get a color wheel and match up 4-5 spots on the portrait to spots on the wheel and record the RGB numbers? Or it there some sort of handheld scanner that will read out RGB numbers? I couldn't find anything, but I didn't know what to search for. I did a search for "rgb scanner" and came up with some sort or hot car accessory. |
#5
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
On 04/04/2013 10:33, Jennifer Murphy wrote:
On Thu, 04 Apr 2013 09:48:48 +0100, bugbear wrote: Jennifer Murphy wrote: I am trying to get a true color photograph of an oil painting. Because of the propensity of the shiny and irregular surface of the painting, reflection has been a problem, requiring some creative lighting set ups. I have several photos taken with different cameras using differnet settings and setups. On my computer screen, they each have slightly diffenet colors. The image will be sent to a printer 3,000 miles away. I would like to be able to ensure that the printed colors are as true as possible to the actual painting. It occurred to me that if I had the exact RGB and/or CMYK numbers for a few spots on the painting, the printer should be able to reproduce it pretty accurately. What's the best way to get the exact RBG or CMYK numbers for the colors on the actual painting? Is there a color wheel I can buy that I can hold up to the painting? Is there some electronic scanner that will show me a readout? Measuring the colours "exactly" will have the same lighting and reflectance issues as your photograph, I'm afraid. Aha. If I shine a red light on it, it will look different than if I shine a green or pure white light on it. So the only way to get the "true" colors of the object is to take it to a carefully controlled environment where it is illuminated by a perfectly balanced light source. This business is maddeningly complex and nuanced. Yes. It depends on the colour temperature of the nominally "white" light too. Some things like Nd doped glass look radically different under sunlight, incandescent or fluorescent lighting. Alexandrite glass ornaments exploit this curious property of certain materials: http://www.20thcenturyglass.com/glas...mium_glass.htm You can quite readily calibrate your shot by including a known target in the photograph, or shooting the target under the same conditions as your photograph. Proper targets aren't super-cheap. Here's a handy page about this: http://www.aff.org.au/AFF2_Eckert_co...al_summary.htm What if I lower my expectations or, at least, make them soemwhat more realitic. Instead of saying I want to get the "exact" RGB numbers, suppose I say that I want to get the RGB numbers for the painting as it looks hanging in my living room under midday ambient light? Use the dropper function inside PSPro or Photoshop to sample the colour and read back its RGB value. CMYK values will depend on the colour model and gamma used to transform from RGB to the smaller CMYK space. Some software will warn you where parts of the image will clip in the print media colour space. Certain programs don't do a good job on this. Could I then get a color wheel and match up 4-5 spots on the portrait to spots on the wheel and record the RGB numbers? Or it there some sort of handheld scanner that will read out RGB numbers? I couldn't find anything, but I didn't know what to search for. I did a search for "rgb scanner" and came up with some sort or hot car accessory. There are some proprietary cards with a hole in that have a bunch of reference colours on and some clever shade matching software that will allow a close enough by eye match to a single colour. Designed by mix your own paint manufacturers to allow DIYers to box themselves into nightmare corners with bespoke custom paints. eg http://www.dulux.co.uk/colours/colourclick/index.jsp Proper colour reference cards are available for photography but they are not cheap and against a textured painting with varnish you are up against multiple problems so they may not help you all that much. -- Regards, Martin Brown |
#6
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
| What's the best way to get the exact RBG or CMYK numbers for the colors
| on the actual painting? Is there a color wheel I can buy that I can hold | up to the painting? Pantone colors are the standard for printing. You can buy fandecks at graphic supply stores. I think they go for somewhere around $60-$100. But you'll need a very good eye for color and a close match in lighting. In my experience it's maddeningly difficult to match a color chip even to wall paint when I know that the color on the wall is an exact match to one of the chips. There's just too much difference in texture, gloss, etc. and that changes the perceived color. (If you really look at a the walls of a room in any light you'll see that there are countless hues and shades -- darker in the corners, less yellow near windows, more yellow near incandescent lights, etc.) |
#7
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
On 04/04/2013 10:33, Jennifer Murphy wrote:
(...) I couldn't find anything, but I didn't know what to search for. I did a search for "rgb scanner" and came up with some sort or hot car accessory. If you're looking for a gadget, the keywords to search with are "handheld spectrophotometer"... Good luck. |
#8
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
In article ,
Jennifer Murphy wrote: What's the best way to get the exact RBG or CMYK numbers for the colors on the actual painting? Is there a color wheel I can buy that I can hold up to the painting? Is there some electronic scanner that will show me a readout? Unless it was a paint-by-number kit, I don't understand how you would expect to be able to do that. Every oil painter I know mixes and blends colors on their pallet and layers and mixes them on the canvas. I think the best you can hope for is to have the printer send you samples to compare to the original, and make adjustments as necessary. |
#9
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
In article , Jennifer
Murphy wrote: Aha. If I shine a red light on it, it will look different than if I shine a green or pure white light on it. So the only way to get the "true" colors of the object is to take it to a carefully controlled environment where it is illuminated by a perfectly balanced light source. This business is maddeningly complex and nuanced. you can white balance for whatever light you use. what you need is a colour managed workflow, as does your printer. What if I lower my expectations or, at least, make them soemwhat more realitic. Instead of saying I want to get the "exact" RGB numbers, suppose I say that I want to get the RGB numbers for the painting as it looks hanging in my living room under midday ambient light? the rgb numbers don't mean anything by themselves. Could I then get a color wheel and match up 4-5 spots on the portrait to spots on the wheel and record the RGB numbers? Or it there some sort of handheld scanner that will read out RGB numbers? won't work. your best bet is include a macbeth colour card in the shot, which can later be cropped out. the printers can adjust the image so the card is correct, which should mean the painting will be correct. they can then crop out the card when printing. I couldn't find anything, but I didn't know what to search for. I did a search for "rgb scanner" and came up with some sort or hot car accessory. i don't see that when searching for rgb scanner. anyway, search on colour management. that will give you way more than you ever wanted to know. if you are near a bookstore, the bible is called real world colour management, by fraser, murphy and bunting. plan for brain overload. http://www.colorremedies.com/realworldcolor/ |
#10
|
|||
|
|||
How to capture exact RBG or CMYK color numbers?
In article , Jennifer
Murphy wrote: I am trying to get a true color photograph of an oil painting. Because of the propensity of the shiny and irregular surface of the painting, reflection has been a problem, requiring some creative lighting set ups. I have several photos taken with different cameras using differnet settings and setups. On my computer screen, they each have slightly diffenet colors. that's expected. The image will be sent to a printer 3,000 miles away. I would like to be able to ensure that the printed colors are as true as possible to the actual painting. It occurred to me that if I had the exact RGB and/or CMYK numbers for a few spots on the painting, the printer should be able to reproduce it pretty accurately. that won't work. rgb and cmyk numbers by themselves don't mean anything. What's the best way to get the exact RBG or CMYK numbers for the colors on the actual painting? Is there a color wheel I can buy that I can hold up to the painting? Is there some electronic scanner that will show me a readout? the way to do this is with a colour managed workflow. you calibrate and profile your monitor and you also obtain a profile for the printer to be used. then, what you see will be what the printer sees. otherwise, you're flying blind. however, you could include a macbeth colour card in the photo for a reference, maybe just outside the actual painting. then the printers can colour balance the image so the card looks correct, and theoretically, the paining will be as well. note that what you see on a monitor can't be perfectly matched by a printer. however, you can soft-proof it on your monitor and get a very good approximation. |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
resample to get exact ppi? | Duncan Chesley | Digital Photography | 3 | August 23rd 06 04:51 PM |
copying exact area? | eugene | Digital Photography | 4 | May 15th 06 04:27 PM |
RGB/CMYK | Conrad | Digital Photography | 4 | February 2nd 06 02:22 PM |
What is exact CR-V3 open voltage? Why does my camera quit on 3.1 volts? | fancy nospam tunes | Digital Photography | 3 | March 5th 05 05:45 AM |
Frame Numbers vs. JPEG Numbers With CF Cards | mort | Digital Photography | 3 | February 16th 05 02:43 AM |