Panorama File size: PTGui vs. competition

[Robert Sch]

I have generated about ten 360*180 sperical panoramas in PTgui and Panorama Studio 2 based on the exactly same (about) ten sets of individual photographs.The results hardly differ in quality, color, stitching errors, processing time etc.

The significant difference however is the file size. In the most extreme case a 7000*3500 pixel panorama generated by PTGui had 18 MB whereas the PanoramaStudio file was only 1.8MB large (i.e. 90% smaller). I could not find any reason for this and I already have a PTgui license. Can someone help me please?

Thanks!

[Fulvio Senore]

A 7000*3500 pixels image has always the same size (at least 3 bytes for
each pixel in a color image). The difference can only be in the file
format used to store the image.

An uncompressed file should be larger than 70 MB, smaller files are the
result of compression.

Anyway, I find it hard to believe that such an image could be compressed
to 1.8 MB without significant degradation.

Fulvio Senore

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[Erik Krause]

Am 21.06.2013 18:49, schrieb Robert Sch:
> The significant difference however is the file size. In the most extreme
> case a 7000*3500 pixel panorama generated by PTGui had 18 MB whereas the
> PanoramaStudio file was only 1.8MB large (i.e. 90% smaller). I could not
> find any reason for this and I already have a PTgui license. Can someone
> help me please?

Most likely you compare apples and pears ;-)

What output format? What compression setting? Layers included?

--
Erik Krause
http://www.erik-krause.de

[John Houghton]

Robert, As Erik suggests, I'm sure you are not comparing like with like.  I generated two 7000x3500 pixel panoramas in JPEG format at a quality setting of 85 in both PTGui and Panorama Studio 2.  The file size was almost identical in each case: 4MB.  Similarly, I generated two TIFF files (8bit packbits compression): the PTGui output was 72MB and the Panorama Studio file was 70MB.  The results did differ in respect of stitching errors.  The PTGui output (in auto mode) was far better, being almost completely free of errors whereas the Panorama Studio result contained several very obvious stitching errors.  But this was just one set of images and may not be typical.  

John

[Robert Sch]

Thanks for your comments, gentlemen!

As you quickly noticed, I am a novice. The default values on Panoramastudio2 and PTGUI give me for one specific set of pictures a 380*180 spherical JPEG panorama with these data:
Panoramastudio2  PTGUI
7000*3500 7000*3500
96DPI  300DPI
2.43MB  19.3MB
both look about equally good to me. In order to get the PTGUI version to 2.4MB I need to reduce the quality in the "Create Panorama" tab to about 85% when I maintain the resoltion at 7000*3500. The other option is to maintain the quality at 100% but then I need to reduce the size to 2500*1250! The result looks rather bad compared to the 2.4MB picture from Panoramastudio2  .

I do not understand this behavior. Can you please give me a weblink to the theory behind it? The point 4.3.of the FAQ section (http://www.ptgui.com/support.html) does not give me the answer.

Thanks!

[Erik Krause]

Am 21.06.2013 22:14, schrieb Robert Sch:
> In order to get the PTGUI version to
> 2.4MB I need to reduce the quality in the "Create Panorama" tab to about
> 85% when I maintain the resoltion at 7000*3500.

85% is a very good and reasonable setting. I guess this simply is the
default setting in Panorama Studio. For most images you can go down to
65% without significant jpeg artifacts.

[John Houghton]

On Friday, June 21, 2013 9:14:05 PM UTC+1, Robert Sch wrote:

I do not understand this behavior. Can you please give me a weblink to the theory behind it? 

It's really straightforward:  both PTGui and Panorama Studio permit the panorama size, file format and compression to be selected according to your particular requirements, but don't necessarily default to exactly the same choices.  However, when you select identical options you get a similar result.  PTGui happens to select 100% as the default JPEG compression, whereas Panorama Studio defaults to 85%.  But you can click on the Options button in the Save dialog of Panorama Studio and select 100% instead if you wish to get a similar result to PTGui.  Likewise, you can select 85% in PTGui instead of the default 100%.

Generally, to mimimize the file size (on disc) you would increase the compression (lower %) to a value where compression artifacts just begin to be noticeable.  The things to look out for are blocking and banding in bland areas like blue sky.  The amount of compression you can get away with is affected by the nature of the image you are compressing.  Busy images with lots of detail compress less well.  Juggle the pixel dimensions of the panorama and the compression to get the file size down to the required value whilst maintaining acceptable quality.  There's no one size that fits all panoramas, though you can devise your own selection of defaults that work adequately for most of your images, according to your display requirements.

John

[PTGui Support]

Hi Robert,

As others pointed out, this only means that PanoramaStudio apparently
uses 85 JPEG quality by default.

The DPI setting is irrelevant, it does not affect the image quality or size.

To learn more about image compression you might want to read:

http://www.dummies.com/how-to/content/getting-to-know-photoshops-jpeg-file-format.html

http://www.worldstart.com/jpeg-compression-basics/

Kind regards,

New House Internet Services BV
Joost Nieuwenhuijse

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