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How to adjust brightness to specified maximum level on some spot automatically - for example - on some spot I want to make brightness not exceeding RGB (250,250,250). I can adjust brightness manually by looking at RGB values at bottom bar - but it's time consuming. Is it possible to do it automatically - by clicking some spot on photo (of course by saving some property before of 250,250,250 - maximum brightness)? Would be nice to have an option to do it automatically at the same time when adjusting/clicking white balance on some spot.

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I'm a regular user of Canon's Digital Photo Professional 4 and I've never noticed any such way to do click on a spot to automatically do it.

Perhaps an easier way to identify when a particular spot is at a certain luminance level is to enable 'Show highlight/shadow warning'. This can be done via the 'Preview' menu, by clicking on the "curves" symbol with an exclamation point at the bottom of the edit pane, or by using keyboard shortcut 'Alt + M'.

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You can then set the parameters of the highlight/shadow warning via 'Menu → Tools → Highlight/shadow warning display settings...' or the dropdown menu attached to the right side of the "curves" symbol with exclamation at the bottom of the edit pane.

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By setting the highlight threshold to '250', any area of the image with an average (all three colors combined) value of 250 or higher will be displayed using the warning color selected in the settings. Default colors are blue for shadows and red for highlights, but you can change them to any of 48 preset or 12 custom colors.

Once you've got the highlight/shadow warning display set up, adjusting brightness, either by using the slider or, even better, the left and right arrows when the brightness slider is active will change the areas that show the warning. It's a little easier to watch the image as you press the right arrow until the spot your curser is hovering over turns red.

Would be nice to have an option to do it automatically at the same time when adjusting/clicking white balance on some spot.

Regarding using the same point to set a maximum value and to set white balance, in general you don't want to use areas that are near saturation to set white balance automatically. If one (or two) channels are fully saturated and the other(s) are not, your results will not be accurate. It's better to use a neutral mid-tone to set white balance. That's why gray cards are "18%" gray that should display as (127,127,127) when "properly" exposed.

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Indeed, as Michael C mentioned, at least now I can see brightness that exceeds threshold level - quite useful (and interesting - how light flows):

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But still - the function by clicking on some spot (as setting white balance function) and setting max. brightness (to entire photo), for example to (or max. R 250, or max. G 250, or max. B 250) - would be great. Perhaps I will try to ask Canon for improvement.

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  • \$\begingroup\$ In general you don't want to use areas that are near saturation to set white balance automatically. If one (or two) channels are fully saturated and the other(s) are not, your results will not be accurate. It's better to use a neutral mid-tone to set white balance. That's why gray cards are "18%" gray that should display as (127,127,127) when "properly" exposed. \$\endgroup\$
    – Michael C
    Jan 29, 2021 at 11:58
  • \$\begingroup\$ This is not about white balance - it's just that I want the same function as white balance picker to adjust brightness.. Perhaps not at the same time. \$\endgroup\$
    – Ernestas Gruodis
    Jan 29, 2021 at 13:14
  • \$\begingroup\$ OK. It sounded on your original question like you wanted to click one spot and set it to (250,250,250) which would both modify brightness and WB. If you only modify brightness and the spot you click is not neutral (i.e. the same value for all three channels) then you'll wind up with something like (245,254,251) or (255,240, 255) for an average value of 250 for all three channels. \$\endgroup\$
    – Michael C
    Jan 29, 2021 at 14:31
  • \$\begingroup\$ The logic is to find highest one of R,G or B channel - and then apply brightness to all picture. For example spot is (254,252,250), brightness setting is set to not exceed 250 (R, G or B each separately). The highest channel is R=254, other channels don't matter. So we need to subtract 4 of all three channels. The result would be (254-4,252-4,250-4) or (250,248,246). Ans so on (-4,-4,-4) to all the rest of pixels. \$\endgroup\$
    – Ernestas Gruodis
    Jan 29, 2021 at 18:02
  • \$\begingroup\$ It's a bit more complex than that if you don't want to change the white balance as well. It's even more complex than that if you want the rest of the image to move in proportion to the bright spot you're using. Moving every (R,G,B) value in the image by the same linear number will change the channel multipliers in slightly different proportions to each other, so it will change the overall effective CT/WB. \$\endgroup\$
    – Michael C
    Jan 30, 2021 at 13:30

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