Converting and resizing images - how do I maintain quality?

I am evaluating the LeadTools API v14. All I am looking to do is convert TIF's to PNG's and optionally resizing them.

I have it working no problem, but the resized image quality is poor. I am wondering how to improve it. Code as follows:

(I included the L_OCXADD.BAS supplied in the \include folder)

    i = L_GetDefaultSaveFileOption(t_SaveOptions, SIZEOFSAVEFILEOPTION)
    i = L_GetDefaultLoadFileOption(t_LoadOptions, SIZEOFLOADFILEOPTION)
    i = L_FileInfo(str_Source, t_FileInfo, SIZEOFFileInfo, 0, t_LoadOptions)
    i_Size = 33 'Resize to 33% of original
    xResize = t_FileInfo.Width * (i_Size / 100)
    yResize = t_FileInfo.Height * (i_Size / 100)
    i = L_FileConvert(str_Source, str_Dest, FILE_PNG, xResize, yResize, 8, 0, t_LoadOptions, t_SaveOptions, t_FileInfo)

We are dealing with simple B&W fax TIF images. The 33% resized image is illegible. Are there options to do this with a higher quality?

I know it's possible. We evaluated ImageMagick and it was able to maintain quality using what they called the "resize" function. They had a "sample" function that was identical to "resize" (both converted and resized an image in a call), but produced the same poor quality I am seeing with the LEAD API code above. Do you have a "resize"?!

 

 

The L_FileConvert function does not have a parameter to control the resizing algorithm. What you could do is the following:
1. Load the image at full size using L_LoadBitmap
2. Convert it to 8-bit grayscale using L_GrayScaleBitmap
3. Resize the image using the L_SizeBitmap function, passing SIZE_RESAMPLE (2) as the last parameter.
4. Save it as 8-bit PNG using the L_SaveBitmap function.

That did the trick!

Thank you so much for the tip!