Adjusting levels in Photoshop changes both image brightness and desktop brightness

[capa150]

Hello.
Blue and white G3, MacOS 8.6. Photoshop 3.
If I open a photograph in PS, and adjust levels or curves for midtones, let's say, then the image becomes lighter or darker (normal). But also the desktop itself becomes lighter or darker the same degree.

Anyone know what's going on?

I noticed the problem doesn't occur with PS 6.0.

 

[Iesca]

May be something to do with the way it's utilizing palettes? Does the desktop goes back to normal after quit, or at least if you restart?

 

[Phipli]

Hello.
Blue and white G3, MacOS 8.6. Photoshop 3.
If I open a photograph in PS, and adjust levels or curves for midtones, let's say, then the image becomes lighter or darker (normal). But also the desktop itself becomes lighter or darker the same degree.

Anyone know what's going on?

I noticed the problem doesn't occur with PS 6.0.

It isn't a problem, its how it works. Are you set to 256 colours? I don't think it does it at Thousands or Millions of colours.

Because changing such things used to be processor intensive to preview, photoshop used to do it in hardware with colour tables. Try using the hue and saturation controls, that messes with the desktop even more

Photoshop 3 is a little old for 8.6 and a G3. No issues, but you could run up to about 7 or so comfortably on that setup.

 

[capa150]

It's set to millions. The desktop goes back to normal once the adjustment is made.

 

[capa150]

Oh Geez. I just discovered another fact:
The problem goes away if I tick the "preview" button in the curves tool.

I took some screen shots to show how adjusting curves also makes the desktop adjust the same amount ... but the screenshots don't show the problem! Ha! How odd.

I snapped some pix with my phone with exposure locked: Last photo has "preview" checked on.

 

[Crutch]

I think, to be both quick and precise, PhotoShop 3 is manipulating the video gamma tables perhaps? (This is for example how one does a quick and efficient “fade to black” in a ‘90s Mac video game.) This can be done instantly because it just changes how the hardware maps pixmaps to display, not the actual pixmap data itself. The side effect is that it impacts everything being shown by the hardware, including your desktop … and it’s not a surprise that it doesn’t show up in the screenshot, since as noted, the actual pixel data isn’t changed by this transformation.

 

[Phipli]

but the screenshots don't show the problem

It really isn't a problem, it's just how things were done.

 

[capa150]

Hrm well I don't recall this happening with PS 3.05 on my PowerMac 7500 with OS 7.6 nor on my IIsi with OS 7.6.
I think it's something with the G3/400 running 8.6. Or maybe a quirk of the ATI Rage 128 card.

 

[Phipli]

I think it's something with the G3/400 running 8.6. Or maybe a quirk of the ATI Rage 128 card.

I'm not sure how to persuade you that it is normal. You asked what is going on and we have told you that photoshop is adjusting the video in hardware to quickly preview your changes. The version of photoshop you are using is designed for machines way older than what you are running it on, and when it was current, computation resources were limited.

If you want it to go away, install a more period correct version of Photoshop, like Photoshop 5.

Edit - even then I'm not promising it will stop doing it, because it is a fast, elegant solution to the problem. It is a /good/ thing. You'd only stop doing it because computers were so fast it didn't matter, or because you couldn't.

 

[PB170]

I don't know if you're convinced yet @capa150 but like @Phipli said, it's very much by design.

It's incredibly helpful to see a live preview of the adjustments one makes, but in the early days of Photoshop, image calculations were fairly processor intensive. So simulating the adjustments by changing the hardware lookup tables was implemented as an alternative.

I've recently had my PowerBook connected to an external display (through the magnificent Radius PowerView ) to get a bit of extra screen space for some special work, and came to think of this thread as I was starting Photoshop (version 2.5) to change the resolution of an image. So I decided to play around a bit.

As you can see, making adjustments using the hardware preview is quite acceptable even on a 25 mHz PowerBook 170:

View attachment LUT.mp4


And this is what happens when checking the Preview box

View attachment Preview.mp4



If you don't like it, you can disable the feature by changing this setting in the general preferences:

 

[PB170]

Some additional information on the topic:

From Essential Photoshop Tips and Tricks

Before version 6 of Photoshop, the Preview checkbox in all the Image Adjust dialog boxes (Levels, Curves, Hue/Saturation, and so on) acted as a switch to turn on and off the Video LUT Animation feature. When the Preview option was off, the video LUT ("look up table") kicked in, altering the entire screen instead of just the image or portion of an image. This was much faster on slow machines, but wasn't always accurate (and didn't work in Windows anyway). In Photoshop 6, Adobe removed Video LUT Animation entirely.

 

[Phipli]

Some additional information on the topic:

From Essential Photoshop Tips and Tricks

Ah, version 6 dropped it. I thought it was around that era but personally I jumped through that era fairly quick. I went from something like 4 to 7.

Interesting info in both posts, thank you.

 

[capa150]

The problem doesn't manifest at all in version 6, btw.

 

[PB170]

The problem doesn't manifest at all in version 6, btw.

I think we need to give you a small award for sticking to describing it as a problem But in support of your view on it, it's a rather crude and far from ideal solution since you lose all onscreen references for the adjustment you make. Probably best to make the adjustments in fullscreen mode and hide as much of the control panel as possible. Anyway, now you know how to make the problem go away should you want to use any version prior to version 6

 

[capa150]

Well I used to use PS 3.05 professionally 1998-2002 at a weekly newspaper. On a PowerMac 7500/100 running System 7.6 (iirc). And I don't recall the desktop ever changing in brightness while adjusting levels and curves. But click off Video LUT in preferences seems more like I remember. Thanks for your help.

 

[capa150]

Speaking of which ... here it is! The foreground Mac is the 7500 I used. Note Mountain Dew, 35mm negative SCSI scanner, police scanner, flatbed scanner (also SCSI). Nikon D1 on the floor.

 

[PB170]

Oooh, very cool! Like it's said, a picture paints a thousand words. Thanks for sharing!

 

[CC_333]

Judging by the overall look and feel of the scene, I'd guess perhaps this photo was taken (on film) sometime during the late 90s? Maybe very early 2000s....

c

 

[capa150]

You are correct. That would have been around 1999-2001 or so.

 

[CC_333]

Neat!

I have vague memories of when offices looked like that.

Fun fact: Around 1999-2001, the local music shop where I was living at the time used iMac G3s for the checkout counters.

A few years later, I think a veterinary office in a different town (we moved in 2004, so this would've been 2005-2007) was still using some, though I think they upgraded to the flat slab style not long after. Or maybe they switched to PCs?

It's been ages since I've seen any sort of vintage Mac in the wild like that (although, they weren't quite vintage yet when I saw them, so....).

c