How to get numerical pixel values from PEF/DNG or TIFF files?

**AstroDave** · 09-12-2019, 10:42 AM

Is there a simple way to get the intrinsic numerical pixel values in an image?

In PhotoShop Elements (PSE), I can see the RGB pixel values as I move the cursor around, but they are in the 0-255 range, and have clearly been scaled by the program (i.e. if you apply, say, the histogram sliders, the values change).

For the K-1 with 14 bits, there should be values in the image file ranging from 0 to 16383 or there abouts.

Programs like MATLAB seem like they can do this, but is there anything simpler that will just show actual unscaled numerical pixel values? Certainly all image processing (and most, if not all, display) programs have these values internally, but I have not found a simple/easy way to get them revealed.

In astronomy, a standard for image files is FITS (flexible image transport system) and analysis programs based on FITS files display the actual pixel values as you scroll around in an image. It sure would be nice if there was something similar for our camera files. Seems to me like it would a trivial add-on to e.g. PSE, DCU5, DxO, etc.

Any ideas?

stevebrot · 09-12-2019, 11:00 AM - **1 Like**

Originally posted by AstroDave

How to get numerical pixel values from PEF/DNG or TIFF files?

RawDigger should be able to do this for you as might LibRaw or dcraw.

Steve

**AstroDave** · 09-12-2019, 11:13 AM

Yeah - I've got a bead on RawDigger

Thanks

**marcusBMG** · 09-12-2019, 11:15 AM

If you use the crop tool in eg faststone, and draw out a crop starting from the bottom left corner, then the size values = x and y values.

**lsimpkins** · 09-12-2019, 11:59 AM

Originally posted by AstroDave

Is there a simple way to get the intrinsic numerical pixel values in an image?

In PhotoShop Elements (PSE), I can see the RGB pixel values as I move the cursor around, but they are in the 0-255 range, and have clearly been scaled by the program (i.e. if you apply, say, the histogram sliders, the values change).

For the K-1 with 14 bits, there should be values in the image file ranging from 0 to 16383 or there abouts.

Programs like MATLAB seem like they can do this, but is there anything simpler that will just show actual unscaled numerical pixel values? Certainly all image processing (and most, if not all, display) programs have these values internally, but I have not found a simple/easy way to get them revealed.

In astronomy, a standard for image files is FITS (flexible image transport system) and analysis programs based on FITS files display the actual pixel values as you scroll around in an image. It sure would be nice if there was something similar for our camera files. Seems to me like it would a trivial add-on to e.g. PSE, DCU5, DxO, etc.

Any ideas?

One of the issues you are seeing is related to the fact that in most cases, the image you see is an RGB conversion of the actual raw fife and therefore limited to 28 values (256) in each channel since RGB is 8-bit. I think Steve has steered you in the right direction.

09-12-2019, 10:42 AM	#1
AstroDave Loyal Site Supporter Join Date: May 2007 Location: Flagstaff, Arizona Posts: 1,646	How to get numerical pixel values from PEF/DNG or TIFF files? Is there a simple way to get the intrinsic numerical pixel values in an image? In PhotoShop Elements (PSE), I can see the RGB pixel values as I move the cursor around, but they are in the 0-255 range, and have clearly been scaled by the program (i.e. if you apply, say, the histogram sliders, the values change). For the K-1 with 14 bits, there should be values in the image file ranging from 0 to 16383 or there abouts. Programs like MATLAB seem like they can do this, but is there anything simpler that will just show actual unscaled numerical pixel values? Certainly all image processing (and most, if not all, display) programs have these values internally, but I have not found a simple/easy way to get them revealed. In astronomy, a standard for image files is FITS (flexible image transport system) and analysis programs based on FITS files display the actual pixel values as you scroll around in an image. It sure would be nice if there was something similar for our camera files. Seems to me like it would a trivial add-on to e.g. PSE, DCU5, DxO, etc. Any ideas?

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09-12-2019, 11:00 AM - 1 Like	#2
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by AstroDave How to get numerical pixel values from PEF/DNG or TIFF files? RawDigger should be able to do this for you as might LibRaw or dcraw. Steve

09-12-2019, 11:13 AM	#3
AstroDave Loyal Site Supporter Join Date: May 2007 Location: Flagstaff, Arizona Posts: 1,646 Original Poster	Yeah - I've got a bead on RawDigger Thanks

09-12-2019, 11:15 AM	#4
marcusBMG Site Supporter Join Date: Nov 2012 Location: North Wales Photos: Gallery \| Albums Posts: 2,869	If you use the crop tool in eg faststone, and draw out a crop starting from the bottom left corner, then the size values = x and y values.

09-12-2019, 11:59 AM	#5
lsimpkins Site Supporter Join Date: Feb 2013 Location: SE Pennsylvania Photos: Gallery \| Albums Posts: 537	Originally posted by AstroDave Is there a simple way to get the intrinsic numerical pixel values in an image? In PhotoShop Elements (PSE), I can see the RGB pixel values as I move the cursor around, but they are in the 0-255 range, and have clearly been scaled by the program (i.e. if you apply, say, the histogram sliders, the values change). For the K-1 with 14 bits, there should be values in the image file ranging from 0 to 16383 or there abouts. Programs like MATLAB seem like they can do this, but is there anything simpler that will just show actual unscaled numerical pixel values? Certainly all image processing (and most, if not all, display) programs have these values internally, but I have not found a simple/easy way to get them revealed. In astronomy, a standard for image files is FITS (flexible image transport system) and analysis programs based on FITS files display the actual pixel values as you scroll around in an image. It sure would be nice if there was something similar for our camera files. Seems to me like it would a trivial add-on to e.g. PSE, DCU5, DxO, etc. Any ideas? One of the issues you are seeing is related to the fact that in most cases, the image you see is an RGB conversion of the actual raw fife and therefore limited to 28 values (256) in each channel since RGB is 8-bit. I think Steve has steered you in the right direction.