encodeImage no support for compression

[varun-raghavendra]

UTIF.encodeImage currently encodes a new Tiff with no compression. This blows up the size of the output TIFF.

Is there a plan to support different compressions like LZW, G4, etc for encodeImage?

Also, could you provide any pointers to build my own image encoder with compression? Unsure how to start off with this.

[varun-raghavendra]

@jardicc, You've mentioned in the below issue that it shouldn't be hard to use existing compression while encoding new Tiff image. Could you elaborate?

[@jardicc] (#102 (comment))

[jardicc]

It was in 2021. I was able to do that for my project. But I would need to spend some time to recall the details. Utif can decode compressed pixels so you would do the same but with encoding.

[photopea]

If you need to store compressed images, I recommend you to use the PNG format instead of TIFF. The PNG is a better format, and it is supported pretty much everywhere.

You can use our library https://github.com/photopea/UPNG.js

[jardicc]

We already had this discussion before. TIFF can support all features as PSD due to Adobe's proprietary section + much more. You can even replace PSD with TIFF and produce smaller files due to better bitmap compressions. PNG is just a flat image ¯_(ツ)_/¯

If you would use PNGs to recreate layers functionality then you would be reinventing a new image format because you would need some "glue".

If I remember correctly to support compression in UTIF... you would need to write about 5 lines of code?

[photopea]

"TIFF can support all features as PSD due to Adobe's proprietary section" you are suggesting to make files, which have the "tiff" extension, but are openable only in Adobe Photoshop.

I really dont recommend to do so. You should use the PSD, if you want layers. PSD files can be opened in more programs, even in some free programs.

[varun-raghavendra]

@jardicc, could you recall what you did in 2021 for your project? Any code reference would be helpful.

[jo-chemla]

Hi there, also interested in adding support for compression to UTIF.js during encoding. Our use case is exporting geotiff from the browser, which has to be tiff.

JPG, LZW, deflate, would be useful.

Seems according to this comment that deflate is already used if pako library is available from window scope. Are you planning to adding more and packaging modules/libraries differently? Thanks!

[photopea]

Yes, deflate is already available. LZW is not better than deflate, it is almost always worse.

I think that JPG inside TIFF makes no sense. It used to make sense 30 years ago, when the TIFF format was 8 years old. Today, you should simply use JPG files instead.

[johnthad]

Yes, deflate is already available. LZW is not better than deflate, it is almost always worse.

I think that JPG inside TIFF makes no sense. It used to make sense 30 years ago, when the TIFF format was 8 years old. Today, you should simply use JPG files instead.

Agreed. Especially as there are two competing "standards": The JPEG-in-TIFF described in the TIFF6 spec (June 3, 1992), and the one described in the "DRAFT TIFF Technical Note #2" (March 17, 1995). LIBTIFF 4.7.0 calls the former compression scheme "Old-style JPEG" and the newer just "JPEG". macOS will not open the older, but it will open the newer one. Moreover, I have seen "Old-style JPEG" implemented two ways. All three of these formats are a pain to deal with.

[jo-chemla]

Thanks both for getting back! The GIS community is used to GeoTiff with different compression techniques for different data. RGB is usually LZW, JPG or ZSTD Digital Elevation Models can use other more accurate, less efficient compression algorithms. See for example this great benchmark guide or also that older, also great example.

Other image file formats cannot usually encapsulate geospatial metadata, so users has to carefully carry over the raw data image file as well as companion files for coordinate system, geographic transform etc - hence geotiff use is superior for these GIS users of massive raster geospatial data. Moreover, with the advent of COG a few years back, Cloud Optimized Geotiffs, the way to store block memory-contiguous, pyramided lower resolution of the raster-data has standardized and matured, with most browser and desktop apps now able to display instantly eg 100k x 100k pixels wide COGs by loading only the area of interest at the resolution corresponding to the user needs.

That's why allowing compression during encoding for UTIF.js would be useful - which eg is used under-the-hood by geotiff.js

[photopea]

I am confused. How exactly can I help you? What exactly geotiff.js can do that UTIF.js can not do?

[jo-chemla]

I was just mentioning geotiffjs because its tiff writer features rely partially on utifjs. So if utifjs can add support for some compression like LZW or JPG during encoding, then these could be ported to geotiffjs as well at some point.

[jardicc]

You should use the PSD, if you want layers. PSD files can be opened in more programs, even in some free programs.

No. I do not need it. Those PSD files are for proprietary use only and will always be opened in Photoshop only. Also those are temporary to store work in progress and usually deleted within week or two. We have a lot of files and this saves some space on our hard drives.

If you do not want to add features to TIFF encoding that is perfectly fine. Your project, your decisions :-) But I suspect you have some bias towards eradicating TIFF file format :-D

[photopea]

@jo-chemla I did not see any mention of UTIF.js in geotiff.js, so I don't think that it relies on UTIF.js