forums.silverfrost.com

[Norm.Campbell]

Hi Paul

This problem has arisen again, this time with 10000s of jpeg files dumped from an AVI file.***

The files can be read by code written in C by a colleague who uses the standard jpeg library files, so the problem is with GET_DIB_*.

Is there any chance of seeing whether there is a simple fix, or whether the solution is more time consuming?


*** If someone has code for reading the individual frames from an AVI file, and writing them as jpegs, that would solve the immediate problem.

[IanLambley]

How about
http://www.dvdvideosoft.com/products/dvd/Free-Video-to-JPG-Converter.htm

[Norm.Campbell]

It is the Free-Video-to-JPG-Converter that is outputting the heavily-compressed jpegs that GET_DIB_* can't read. GET_DIB_* doesn't recognise the content of these jpegs (nor those from a number of other AVI > jpeg converters).

What I need to do is read the outputted jpegs, stretch the intensity values to maximise the colour range (and possibly also remove the differential illumination effect), and write a new set of jpegs.

If I read a jpeg into Photoshop and export it as a jpeg, then GET_DIB_* works fine.

[IanLambley]

I've had problems with jpegs from one type of camera which could not be read by the FTN95 routines.
I used the batch processing facility of Irfanview (it is free) which allows conversion of one type if image to others but it will change jpegs to jpegs with the only change being that the when it writes out the converted, it can be read by the FTN95 system.
Ian
So basically if you open Irfanview and drop one image onto it, pres "T" for the thumbnail view, select everything and use the "File, Start Batch process with selected items" option of the thumbnail window. and hit the process button. It will remember your settings for next time.

[Norm.Campbell]

Thanks, Ian, that could be a reasonable solution in the short term.

At present I have to convert all the files to uncompressed tiffs, using some C code that a colleague has written based on the standard jpeg library, and then use my own code to read the tiffs, process the files, and output them as jpegs.

This is messy, and I still think that Silverfrost should modify GET_DIB_* so that it can handle jpegs that conform to the current jpeg standards.

Norm

[PaulLaidler]

I am not sure that this is relevant but here is an extract from the current ClearWin+ enhancements file. It applies to version 7.1 of FTN95 and after.

GET_DIB_SIZE@, GET_DIB_BLOCK@ and IMPORT_IMAGE@ have been extended in order to provide access to a wider range of image files
via the Microsoft GDI+ library. This change removes current restrictions on the type of JPEG files that can be accessed and
extends the access to image files of other types in addition to the existing access to JPEG and BMP files.

Users can activate the extended features via a prior call to USE_GDIPLUS_IMAGE_FILES@

INTEGER USE_GDIPLUS_IMAGE_FILES@(state)
INTEGER state

A positive value for "state" enables GDI+ in this context.
A zero value for "state" disables GDI+ in this context.
The function returns the former "state" before the call.

The default "state" is zero (OFF).