Thank you for your detailed reply. The most important thing is that it is not hopeless nor impossible to be done in FPC, but it would be much easier if we could know more precisely if we have enough memory available for loading a certain image, or how to estimate the tiles' dimension.
I observed memory consumption in Windows Task manager of applications using Imaging. Out of memory exception occurred sometimes even at 600MB of the application's memory consumption, and on the other side, even above 1,2 GB would not raise the exception. What would you suggest, how to cope with this memory consumption issues?
Thank you anyway for this really amazing library and keep up in further improving it.

After further testing, I can say that the problem occurs when an application is trying to convert from R8G8B8 to A8R8G8B8. So maybe there was sufficient memory for 3, but not for 4 channels. But the question is: How to estimate the memory limit (MemAvail() is available?) and how to overcome that limit. Is there any chance that Vampyre Imaging Library would be capable of opening those files and up to about PSD file limit (30000px x 30000px x 3 or 4 channels) in any (development) environment (Linux, Windows, FPC, Delphi...)?

I performed the following test: Used VampConvert demo console application and successfully converted my 8504x9213 PSD file into .bmp and .jpg. Loading those .bmp and .jpg files FAILED IN LCLImager.exe with the same exception: Out of Memory.
So, my PSD file being successfully loaded by VampConvert, I converted the corresponding Delphi project VampConvert.dpr into Lazarus project and built VampConvert.exe. Then I repeated the conversion of my PSD file to .jpg and .bmp with this FPC-compiled VampConvert.exe WITH THE SAME SUCCESS! Hence my PSD file was successfully loaded and converted by FPC-compiled VampConvert.exe. And again, NO USE OF LOADING either .bmp, .jpg, or .psd 8504x9213 file in LCLImager.exe.
I really hope these test results will be useful for finding out what could cause the Out of memory exception.
Thank you in advance for any support.

Thank you for your immediate reply. I have 2GB RAM, so it is not a problem, I suppose. I 'll surely make the test you suggested and let you know about the results as soon as possible.

When trying loading of an 8504h x 9213w PSD A8R8G8B8 image to the LCLImager demo application compiled in Lazarus 0.9.30 with FPC 2.2.4 in Windows XP, I get the following exception message:

Out of memory.

Is there any memory size limit for psd images or is it a bug?

Additionally, when trying loading the same image in Delphi-compiled VCL Image Browser (ImgBrowser.exe) demo application, everything works fine.