Lightroom local adjustment bug, and workaround

The bug

This is not a new bug: In fact, it was already present in Lightroom 2. However, since it’s still unfixed in LR 3.5 I decided to put it on the blog anyway. Surprisingly few users know about the bug, so it might help someone.
If you are using the Local Adjustment Brush or Gradient tool in Lightroom 2 or 3 with any kind of exposure correction (even a negative value!), you might be in for a surprise: No matter where you brush, highlights will clip in the entire image.

Example

Here’s an image, straight out of the camera, Adobe defaults applied, except that I’ve set “Camera Neutral” as DNG profile. Note that parts of his temple are not quite blown.

Image using Adobe Defaults

Here’s the image after I applied a local adjustment of -0.32 exposure (Default “Burn” setting in LR3) to the lower left corner: Entire temple area blows out big time.

Local Exposure Adjustment blows out highlights.
Read the rest of this entry »

Clipping Warnings in Lightroom

And why they deceive you

Adobe Photoshop Lightroom, like many other Raw converters, has a clipping warning.
The purpose of it is to give you a visual warning (apart from the histogram) of what parts of an image might be clipping.

What is clipping?

A pixel is clipping when it reaches a value of 0 or 255 in one or more channels, and “should have gone further”. Since it cannot go lower then 0 or go higher then 255, it remains at those values: Detail is lost if one or two color channels clip, part of the image is solid black or white if all 3 channels clip.

The effect of color space

As with anything in digital imaging, the color space used has a big influence: A wide gamut color space (such as ProPhotoRGB) will have lower values for the same color then for instance sRGB. So a color that is clipping in sRGB, need not be clipping in ProPhotoRGB! Read the rest of this entry »

Firefox 3.5.1

and LUT profiles

In my previous post, I wrote about Firefox 3.5 “better wait for version 3.5.1”
That version was released today, and I’m sorry to say, It still has its problems:
For one thing, it still doesn’t support ICC V4 profiles.
For another, by default it color manages like Safari does: Wonky: Only images with embedded profile are managed. So you could get problems as described on this page: The image looks different from the background.
On my Mac, it didn’t. What the heck? I hadn’t changed it from the default setting…
No matter what I set in the “gfx.color_management.mode”, it looked like the thing kept managing everything (except when setting “0” off course). No way to get the images on that page to look different from the background. “Here be dragons” indeed.

But wait, there’s more

The background looked different from the background of the same page opened in (fully colormanaged) Flock 2.5. In fact, the background looks like the page opened in Safari. Yet there was no change on the images with and without profile. Another “what the heck”? I’d already checked that images with embedded profile were color managed… Read the rest of this entry »

PSCS4, OsX and Epson…

part 2, not the best news

In my previous blog post about the subject, I mentioned a workaround for the bug, and also said I didn’t like the idea of converting to GenericRGB somewhere in the process since it might clip colors…

Gave it a quick try today, and yeah, it does clip “somewhat”…

Same image as last time. Original is AdobeRGB. In this image, some purples and dark blues are out of gamut for the R2880, using Epson Premium Glossy paper. Admittedly, not your “average” color palette, but one that does show problems if they are there.

Softproofed

Let’s start by showing the original converted to sRGB; Read the rest of this entry »

PSCS4, OsX and Epson…

don’t seem to play nice together.

When testing my Epson R2880 on PSCS4, it was quite obvious that something was off; The print came out looking nothing like the softproof on screen.

To give an indication of what it looked like: Here is a splitscreen: Top left is the softproofed image, bottom right is what the print looked like:
(screenshot converted to sRGB for web display: The difference is bigger in print)Softproof vs. print

The same image printed from PSCS2 was a perfect match to the softproof. Very weird.
I remembered that another photographer had complained to me about similar issues, and showed me some pdf files in preview. (In OSX you can preview a print as pdf file in Preview).

So I tried that. What a surprise: pdf generated when printing from PSCS2 was entirely different from the one using PSCS4. Same printer driver, same settings in Photoshop, same everything.
Neither of the pdfs looked even remotely like the respective prints by the way. The PSCS4 pdf looked like the softproof (as did the PSCS2 print).

Getting weirder by the minute.

A search on the net only brought up a “Double profiling” issue in OSX 10.5.something. Not what I was experiencing. Also, I’m running 10.4.11.

So, I decided to investigate further.
The pdf generated when printing from PSCS2, has an AdobeRGB1998 profile embedded. No idea why, since it is obvious the wrong profile (should be the paper specific profile for the R2880 I’d think, but that also isn’t the case)
Even weirder, the PSCS4 pdf, had a GenericRGB profile. What? Why on earth… That one has an even slightly smaller gamut then sRGB as far as I know…

Workaround

Some messing about testing with profiles followed.
It turned out that converting the PSCS2 pdf to GenericRGB, then assigning the paper profile, gave two identical images (easier to compare that way around, since the pdf coming out of the PSCS2 print path was very saturated and weird looking because of the wrong profile). Both were now again looking like the softproof in Photoshop.
So, doing the reverse (Convert to paper profile, assign GenericRGB) should give a decent print out of PSCS4. (at least, looking at the pdf. Haven’t wasted any paper on it yet).

So far for a workaround, now for the explanation…

Including “GenericRGB” in the search term proved to be a good idea. On the Adobe Forums I found a thread about grayscale printing (no wonder I hadn’t found it earlier).
In that thread Eric Chan explains how OSX Leopard will convert the image data to Generic Gray or Generic RGB before handing it off to the driver. So, yeah. That’s likely to screw things up…
I’m still not sure why or where the PDF out of PSCS2 gets an AdobeRGB profile. Seems rather silly if you ask me.

I might use the workaround when in PSCS4, or print from PSCS2 until this issue gets fixed… I think I’ll mostly use the latter, since I don’t like the idea of converting to GenericRGB somewhere in the process; it might clip colors without me having any control…
Have to compare a few prints, to see if there are differences.

Edit: The workaround does have its drawbacks: See my next blog post.

(Apple and Epson: Are you reading this?)

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