Inspiring

Answered

Merge Down Gives Unexpected Results

Forum|Forum|3 years ago
May 21, 2022
2 replies
2510 views

Hi,

I am geeting an unexpected result from the 'Merge Down' of layers. Under certain circumstances, when I Merge Down an image which appears full colour on the screen, the layer icon goes monochrome and the image will only save in monochrome. The details are as follows.

I load the image (Test Image below) and I create a duplicate layer (Background Copy). I apply the 'Graphic Pen' filter to the new layer and I then set the blend option to luminosity (Screen Shot 1 below). I now select 'Merge Down' for the Background Copy layer. The image remains in colour mode but the layer icon is monochrome. (Screen Shot 2 below). The image will now only save in monochrome.

Can anyone suggest a work around so that I can save the colour image. Thanks

Windows

Correct answer D Fosse

From the menu View > 100% or shortcut ctrl+1.

100% is a significant number, because it means one image pixel is represented by exactly one physical screen pixel. This is the only way to see the actual pixel structure in the file, without any scaling or resampling.

Then take one screenshot before merging, and one after merging, and post them here.

Zesty_wanderlust15A7

Known Participant

"Can anyone suggest a work around so that I can save the colour image. "

Image > Duplicate... (check the option)

Does it do the same thing there? If not, you can save that way.

If you're merging down anyway, you can save in any image format you like w/o merging down.

T

terence21981657g3ekAuthor

Inspiring

Thank you for your response. 'Duplicate image' duplicates the image in monchrome.

Yes I could save the image in say .psd but then it would only be good for viewing in a Photoshop environment. As far as I can tell (from my limited familiarity with Photoshop print) the image will only print as monochrome.

Zesty_wanderlust15A7

Known Participant

Ok, that's no fun then...

Yes, I know you want a file to use, but I'm just saying you can save or export that at any time — you don't have to merge down to save a jpg, png, tiff, etc. (although if you want .tiff that keeps your layers, you will of course save a lot of space by merging down, but... have no layers LOL)

So, if you don't mind merging down (as you are doing that), I'm saying you might as well save it out as a file (= skip the merging down and even throw out the psd if you like). Of course, preferably you'll want this file to be a non-lossy format (tiff, ...) so you can do further work later.

c.pfaffenbichler

Community Expert

Could you please post a screenshot taken at View > 100% with the pertinent Panels (Toolbar, Layers, Channels, Options Bar, …) visible?

»The image remains in colour mode but the layer icon is monochrome. (Screen Shot 2 below). The image will now only save in monochrome.«

How so? It appears to have color on screen, does this disappear after re-opening the image?

T

terence21981657g3ekAuthor

Inspiring

Now that I understand the requirement for 100%, I have posted a screenshot in response to another contributor. The image is monochrome under ‘100%’ but coloured under ‘Fit screen’ and it is possible to flip between these two states.

I am still asking if someone else can take just two minutes to implement the same processing sequence as I describe here and advise whether they see the same anomaly or not.

D Fosse

Community Expert

‘The faulty display at the smaller magnification is irrelevant.’

I know that now but you can’t seriously expect users to anticipate this without some mechanism or warning message to alert them to this anomaly. Basically, the on-screen image is different from the layer icon and most users would regard this as an implementation error. If the icon is correct then the larger display image should be correct also.

I understand how the blend mode works what I had failed to fully appreciate was the fact that the particular filter only produces outputs that are (0,0,0) or (255,255,255) and these cannot carry colour. From my viewpoint the solution is to apply a 1 pixel motion blur to the Graphic Pen image along the stroke direction. I attach the example image processed in this way.

All adjustment and blending previews are calculated based on what you see on screen at any time. So if you're zoomed out to fit the image on screen, it's calculated from this downsampled version. In other words, many image pixels are averaged out to very few screen pixels. A large array of black and white pixels come out as a small number of gray pixels.

Only at 100% is this mapped 1:1.

It's always been done this way for performance reasons. It could be done so that all calculations were always performed on the full image data - but that would increase CPU load, GPU load, and not the least memory and scratch disk usage, by a significant amount. It might work on a high-spec desktop machine, but bring an average laptop to its knees in seconds.

As hardware improves over time, so do average file sizes to take advantage of that. The ratio between them doesn't change nearly as much.

I'm not saying there is no solution to this, but it's not nearly as simple as it would seem immediately. It would be nice to have a choice, and take the performance hit, with a setting in Preferences. It used to be possible to set cache levels to 1, which would do exactly this. But that's no longer possible for some reason.

In a "normal" continuous-tone photograph this isn't a problem. It's only a consideration with binary or very noisy images where one pixel can be very different from its neighbor pixel.

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