Trim isn't trimming all transparent pixels

[Guest]

I have a .png which has some transparent pixels to the right. If I go to trim and select transparent pixels, it doens't work. If I select the image (leaving the transparent pixels) and go to "crop", then it doesn't crop to the image and leaves the transparent pixels. What am I doing wrong? 

[JayBeeM]

Well, this one for example.

In my Photoshop it will leave a row of 16 pixels top and bottom when trimmed based on transparent pixels all sides.

[c.pfaffenbichler]

Sloppy clipping has consequences. 

[JayBeeM]

Hmm... point taken.

But since I'm getting lots of my matrial from other sources I guess "sloppy clipping" is the norm than the odd occurance.

Fact is, I can't remember the last time the trim command actually effectively trimmed the background from anything. And working with Photoshop for more than 20 years I will swear the success rate has gone downhill.

The working steps is usually to go for the trim - see that it doesn't work (this is where I suspect will probably say it works as it should) - then trim the image manually while cursing at the useless trim command. Perhaps adding an option for more tolerance of invisible dust-pixels is an idea?

[c.pfaffenbichler]

And working with Photoshop for more than 20 years I will swear the success rate has gone downhill.

That is not Photoshop’s fault. 

As far as Photoshop is concerned a pixel with 1% opacity is not an »empty« pixel, if your contributors think differently they appear to be mistaken. 

I would recommend applying »Stroke« (set to »Position: Outside«) and checking the image at View > 100% before invoking Trim. 

I think it would be possible to automate a Trim to something else than completely transparent pixels with a Script, maybe even with an Action. 

[c.pfaffenbichler]

Just to clarify: I don’t claim that I don’t occasionally miss stray pixels, too, even after using the Stroke-check. 

[Conrad_C]

Perhaps adding an option for more tolerance of invisible dust-pixels is an idea?

By @JayBeeM

The idea of a threshold just occurred to me too, and you might consider posting that as a feature request in the Ideas section of this community…that’s where feature requests are formally evaluated separately from the general help questions here.

As for the Trim command being useless or less effective…no. It does exactly what it is asked to do. That’s why I asked if you had an example. Because as far as I know, every time this has come up, when the example was examined we have been able to show that there was a non-transparent pixel outside the intended area. The option is to trim transparent pixels, and it does exactly what it says, a pixel with even 1% opacity doesn’t get trimmed, so no bug.

However…the intention of the command is to make life easier, so in a world where people constantly hand you work that’s not properly cleaned up, the fact that it’s very difficult to notice a pixel with 1% or 2% opacity can screw up trimming, and this does seem like a problem that computers should help solve. Your idea of a threshold might be one approach, not sure if there are any unintended consequences from that but it’s worth asking Adobe to explore it. Or, a better algorithm or AI could help support the intention of this feature, rather than always taking it literally, which gets screwed up by stray or low opacity pixels.

As for me, when this happens, once the non-transparent pixels are identified I drag a rough lasso or rectangular marquee selection around the area and hit Delete to nuke anything that shouldn’t be there, then Trim again.

[Conrad_C]

That’s a nice technique, using the Stroke effect. I think I’ll start using it instead of the Threshold technique I posted earlier in the thread.

Case closed...not a bug.