Timo Autiokari
17th of February 2003 (Mon), 02:42
Hello all D60 users,
A memeber on my forum asked why his linear 16-bit/c TIFFs (converted using the Canon ZoomBrowser on PC) only gives image data for the digital range from level 0 to to level 215 as seen from the Photoshop's Histogram dialog, on the "Luminosity" channel, even if the image is overexposed.
He even uploaded a test CRW and I got the same result after converting it with the ZoomBrowser 3.3, I used Photoshop 7.0.1 to examine the histogram. No color conversion or profile conversions were made by Photoshop when opening the TIFF.
Ok, I took a similar test shot with my D60 and royally irritatingly it codes the overexposed image to the levels range to about 0 to 200 (Red is 203, green is 200 and blue is 198). There is nothing in the range 200...255 no matter how much I overexpose.
However the histogram that the D60 Info shows on the LCD clearly shows that the shot is overexposed, there is a rather large peak at the very right edge of it and there is image data in the range from level 200 to level 255.
So, there seems to be a bug or someting peculiar somewhere on the 16-bit/c path from the D60 camera to Photoshop.
I hope that some D60 owners here could please repeat this simple test.
1. Just take an overexposed shot of what ever (e.g. take an indoor shot during daytime so that a window fills about half of the image) expose for indoor. Verify that the D60 info shows the blinging white/black areas and that the D60 histogram has a hefty peak at the very right edge of it.
2. Convert to Linear 16-bit/c TIFF using the Canon RawConverter 2.
3. Open to Photoshop without color conversion (and do not worry if the image appears to be dark, it depends on your working-space ICC profile how the image appears at this stage) then examine the Histogram (all the channels: "Luminosity", Red, Green and Blue). What are the highest values of the histogram on each channel?
Thank you very much for your help.
Timo
A memeber on my forum asked why his linear 16-bit/c TIFFs (converted using the Canon ZoomBrowser on PC) only gives image data for the digital range from level 0 to to level 215 as seen from the Photoshop's Histogram dialog, on the "Luminosity" channel, even if the image is overexposed.
He even uploaded a test CRW and I got the same result after converting it with the ZoomBrowser 3.3, I used Photoshop 7.0.1 to examine the histogram. No color conversion or profile conversions were made by Photoshop when opening the TIFF.
Ok, I took a similar test shot with my D60 and royally irritatingly it codes the overexposed image to the levels range to about 0 to 200 (Red is 203, green is 200 and blue is 198). There is nothing in the range 200...255 no matter how much I overexpose.
However the histogram that the D60 Info shows on the LCD clearly shows that the shot is overexposed, there is a rather large peak at the very right edge of it and there is image data in the range from level 200 to level 255.
So, there seems to be a bug or someting peculiar somewhere on the 16-bit/c path from the D60 camera to Photoshop.
I hope that some D60 owners here could please repeat this simple test.
1. Just take an overexposed shot of what ever (e.g. take an indoor shot during daytime so that a window fills about half of the image) expose for indoor. Verify that the D60 info shows the blinging white/black areas and that the D60 histogram has a hefty peak at the very right edge of it.
2. Convert to Linear 16-bit/c TIFF using the Canon RawConverter 2.
3. Open to Photoshop without color conversion (and do not worry if the image appears to be dark, it depends on your working-space ICC profile how the image appears at this stage) then examine the Histogram (all the channels: "Luminosity", Red, Green and Blue). What are the highest values of the histogram on each channel?
Thank you very much for your help.
Timo