As described in another post, I acquired thousands of JPGs, and used various tools and techniques to create long, informative filenames that would help me to sort those JPGs into various categories. I started by separating out a smallish number of images worth investing time and space to present in video format. Video would consume disk space, and could take a lot of time to prepare, but would allow me to combine these images with other pieces of video, along with assorted audio recordings and other materials.
Most of these images did not merit that kind of investment. After separating out the ones whose contents and quality meshed with my video editing plans, I was left with 5,592 JPGs (filling 5.6GB of disk space) that just needed to be archived in some moderately accessible way. I was particularly interested in the possibility of a slideshow. A slideshow approach to archiving would have the advantage of making all those JPGs viewable without having to move through them manually, one click at a time. That, I knew, I would rarely if ever do. So this post describes the steps I took toward converting these images into a slideshow, and concludes with a comparison against the ZIP and PDF options discussed in the other post.
Note that any type of file (and, in my experience, PDFs especially) can become unreadable. Losing one or two JPGs is quite different from losing the MPG, PDF, or other file containing the entire set of hundreds or thousands of images. An effort of the sort considered in this post should be accompanied by a careful backup system and, ideally, by a regular system for checking PDFs. (Note: a later post provides updates on some topics discussed here.)
Microsoft Photo Story
The first step was to find good slideshow software. There appeared to be many contenders. For instance, one webpage offered a list of the 21 best free Windows slideshow makers. That page agreed with others (e.g., Gizmo) in putting Microsoft Photo Story (3.8 stars at Softpedia) at the top of the list. In the present case, however, when I attempted to create a Photo Story slideshow containing 5,592 JPGs, I got an error message:
Photo Story 3 for Windows
Some of the pictures you selected could not be imported because the film strip contains 300 pictures, which is the maximum number allowed.
Although I didn’t plan to make a video of these 5,592 JPGs, I did try importing them into Adobe Premiere Elements, just to see what would happen. Like Photo Story, it balked at anything more than a few hundred files, though possibly it would have handled them if I had attempted multiple imports of smaller numbers of files.
Wondershare DVD Slideshow Builder
Trying again, I followed Callum Fallon‘s advice to try Wondershare DVD Slideshow Builder ($50; free trial). It advertised the ability to handle any number of photos, as well as various transition and special-effects options. I found it was able to import the 5,592 JPGs, in a “Processing” phase that took maybe ten minutes. For each picture, its Organize tab offered basic image-editing options (e.g., crop, flip, hue, brightness, auto-repair), as well as the option to create and adjust a caption, with text effects (e.g., scroll, fade). Its Personalize tab allowed for dozens of different transitions options between slides, motions (e.g., zoom) within slides, clipart additions, and effects, as well as introductory and credits slides. The Personalize tab displayed each photo with a slide number, in a storyboard across the bottom of the screen (there was also a timeline option), but there did not seem to be a way to make that slide number or filename the default title of the slide. (I did not expect to need it, but it seemed advisable to build in some way of referring to individual slides.) The program’s Settings allowed for adjustments to aspect ratio, duration of photos and transitions, and soundtrack synchronization. Changing the duration to 0.25 for photos and 0.0 for transitions did not seem to work: the preview continued to display slides for the default 4 seconds, with an unwanted (apparently default) rotating zoom transition. I had to remove all clips and re-import my 5,529 JPGs to make the changed setting work. The preview now displayed a 0.25-second duration. That very rapid duration was on the margin of viewability; it worked here because this set had many near-duplicates that VisiPics et al. had not detected.
Wondershare’s Create tab gave me the option of exporting video in a variety of formats. My suspicion, now confirmed, was that a slideshow presentation that might contain moving imagery (e.g., zooms, transitions) would be exported as a video file. As noted above, this could require substantial disk space. The program offered a good variety of video formats (e.g., MP4, WMV) with resolutions up to 720p and rates of up to 30fps. There would be the option of using Wondershare, or something like it, to produce a slideshow video that a video editing program like Adobe Premiere Elements would then be able to handle, where it couldn’t handle the 5,592 individual JPGs. In this case, I tried the lowest possible audio (64 kbps) and video (256 kbps) bitrate settings, with resolution of 1280×720 in MP4 (H.264) format. There was no option to turn off audio. (At this output stage, I saw that the Wondershare trial version was going to watermark the video.) These settings produced a 275MB file. Windows Explorer > Properties > Details indicated that, despite my settings, the output file actually had a video bitrate of 1644 kbps and an audio bitrate of 3 kbps. The watermark was so obtrusive as to make it difficult to get a feel for the quality of the video. It did appear that the photos may have lost some quality.
I had previous experience in creating an IrfanView slideshow. In that case, I was handed a set of 2,500 photos from someone’s vacation. I didn’t feel like moving through them manually. I did want to see them, but had only limited curiosity about their contents. I decided to combine them into a slideshow that would display images at a rate of two per second. That gave me a slideshow lasting about 20 minutes. I think I actually did watch it all the way through once — which was more than almost anyone else (possibly including the photographer himself!) could say. At that pace, it was not necessary to worry about imperfect or duplicate photos; they just mingled into the flow.
So naturally it occurred to me to try IrfanView again. The output would be in the form of an EXE (i.e., self-executing) file. This was, in many ways, a barebones alternative. For one thing, IrfanView offered no playback option of slowing down or backing up a few slides. Instead, the EXE output would resolutely march through the list of slides, from start to finish, at the pace specified at the time of file creation, offering only a few basic controls (e.g., pause). I would have to use screen capture software to convert the EXE to video, or take screenshots to export individual images. There was an option to include a soundtrack, but there was no audio fine-tuning, and no motion features (e.g., zoom, fade) — just images. On the positive side, while I couldn’t add captions to individual slides, IrfanView did allow automatic display of filename, Exif information, and a few other items on each slide, albeit without formatting options.
IrfanView recognized that my stack of files inadvertently contained one PDF, and refused to process it, leaving me with an actual count of 5,591 JPGs. Likewise Wondershare, though in that case I had to scroll to the end of the storyboard to see that only 5,591 slides were included, whereas IrfanView had stated how many files it was including.
I chose an output size of 1280×720. IrfanView processed the files quickly, producing its output within about two minutes, while Wondershare had taken more like 15 minutes. I could have specified any output size in IrfanView: I just had to type the desired numbers into the relevant boxes. Unlike Wondershare, apparently, IrfanView would preserve the quality of each file. I wasn’t even sure that it would downsize the output for those containing excess data. When I fed it more than 4GB worth of files (which, it said, was the maximum size of its EXE output files), it created 4GB EXE files that were unplayable. When I used IrfanView’s batch editing feature to make copies of these JPGs, resized to be no more than 1280 pixels wide, I wound up with 3.2GB worth of files, and they produced a 3.2GB EXE.
It seemed, in other words, that if I didn’t mind the EXE format, the barebones options, and other aspects of the IrfanView approach, I should begin by deciding how much quality I needed and how large a file I was willing to tolerate. Wondershare (and, probably, other video slideshow programs) would be thinking in terms of bits per second, which didn’t necessarily tell me much about quality. But if I could stand to archive these files at a reduced quality level, I might save a bunch of space.
On that basis, I tried again. This time, I resized the files to be no more than 720 pixels wide. Their total size was 1.5GB. Then I made a 720×480 EXE from those resized files. Sure enough, 1.5GB was also the size of the resulting EXE. That was also the size of an EXE created from those same files. I created another EXE, this time 1280×720, from the same 720×480 files. The advantage of the latter was that it played back in a bigger window. (The window size could not be altered during playback.) Here, again, the output EXE was 1.5GB.
From these experiments, I concluded that the IrfanView slideshow output EXE would have the same filesize as the input files. To keep filesize down, I could convert the input JPGs to lower resolution. To have a larger output display, I would designate a larger size in the slideshow configuration. The choice between IrfanView and some other program would apparently depend upon these considerations, and on the programs’ respective advantages and disadvantages.
I had previous experience with NCH software. On one hand, they used to have an annoying habit of adding a bunch of unwanted icons to my Windows start menu, and nagging me for various things. On the other hand, I found their stuff to be really good. The Debut screen capture tool (around $10 or $20, as I recalled) had given me years of good service, capturing video very effectively. So now I wondered how their PhotoStage slideshow program would fare.
Sure enough, on installation, I found two new redundant sets of icons in my Start Menu. Aside from PhotoStage, the icons in these sets were basically adware: they were links to other NCH programs that, if clicked, might run and might or might not require immediate or eventual payment. So I had to prune out most of that crapware.
Once I got PhotoStage running, as with Wondershare (above), I started by adding the 5,591 JPGs to my project (via the Add Photos button), and it took its sweet time looking at each photo it was adding. I didn’t time it, but it seemed to to take more than 15-minutes. I’d say 30 to 45 minutes. I dragged the imported JPGs from the Media tab down to the timeline. That took a while too.
I saw now that the photos on the timeline had a default duration of 3.0 seconds, with 0.5-second transitions. PhotoStage was willing to set resolutions as high as 1920×1080, but I went with 1280×720. I set it to the same 0.25-second duration as with the Wondershare project (above), and no transitions. I also changed the cache location. There did not seem to be an option to automatically number each slide. Then I clicked OK. It said, “Cleaning up cache” and took a while longer. But it wouldn’t exit the Options. After waiting for it to finish cleaning up the cache, I clicked OK again, and it said “Cleaning up cache” again. Same thing, a third time. I clicked Clear Cache and waited again. Eventually it gave me a balloon error, indicating that it would not accept a transition of less than 0.2 seconds. I set 0.2 seconds, made sure Default Transition Type was set to No Transition, and tried again. That worked. But now I saw that, as with Wondershare, the timeline had not changed. When I exited PhotoStage, it showed me an advertising webpage.
I restarted PhotoStage. I saw, in its Options, that it had not accepted 0.25 as a duration, but rather had rounded it to 0.3 seconds. As before, it took a while to load the JPGs, and then to respond when I dragged them down to the timeline. The timeline did not verify the number of slides involved, but did provide a total time estimate of 27:57.3, which (at a rate of 0.3 seconds per slide) worked out to 5,591 slides. I went to File > Export Slideshow > File Format = .mp4, Resolution = 1280 x 720, minimum audio, H264. I did this twice. The first time, I moved the quality slider to the minimum quality limit. Within a few minutes, PhotoStage produced an MP4 of only 33MB. Windows Explorer > right-click > Properties > Details tab reported that this file was indeed 27:57, 1280×720, with a data rate of 160kbps and 10 frames per second. It played, but the video quality was very poor, as the file size would suggest: the slides were extremely pixellated. I tried again, this time with the quality slider set to maximum. Again, PhotoStage produced the video quickly. This time, the MP4 was 1.9GB, with a reported data rate of 9934kbps and, again, 10fps. Image quality was comparable to the original, viewed at the same size, though it appeared some color settings (gamma, perhaps) varied slightly, at least on some slides.
The second time I exported the slideshow, PhotoStage reminded me that this was a trial version, and gave me an option to purchase. I said “later” and proceeded. But it appeared likely that I would have to purchase eventually, if I continued to use the program, at a price of $25 for the home edition (lacking “video clip insertion support”) or $35 for the professional version.
So it seemed that PhotoStage, and probably other slideshow software, would be capable of producing a slideshow from these thousands of slides. As noted above, there were numerous other slideshow programs to choose from. My own continued search would probably include Windows Movie Maker (4.2 stars from 799 raters at Softpedia), YouTube’s own slideshow maker, and perhaps ffDiaporama (portable version: 4.7 stars from 13 raters at Softpedia).
But now, as I viewed the video produced by PhotoStage, there had to be serious doubt as to whether I, or anyone, would actually sit through a half-hour slideshow, displaying pictures of mixed quality and interest at a rate of four per second. Without numbering, without captions (and enough display time to read them), and without investing the time to organize the images sequentially (and, perhaps, to insert and record the locations of section divider slides), there was also a question of whether it would be possible to locate any individual photo, should I ever want to do so. It seemed that perhaps I should reconsider the concept.
PowerPoint & LibreOffice
For a different approach, I fired up Microsoft PowerPoint 2016. With an untouched new blank presentation onscreen, borrowing somewhat from the older advice of Bennet, I went to Insert > Photo Album > Insert Picture from File/Disk > select all of the desired files > Insert. After a delay, this presented me with a “Convert File” dialog. It appeared to be asking what format the image was. I indicated JPEG File Interchange Format. It asked again for another file, and another. Then it said, “An error occurred while importing this file.” This happened several times. It appeared that I might needed to convert or resize these files before attempting the import. To bail out, I had to kill PowerPoint via Windows Task Manager.
Using IrfanView, I made resized copies of all files, setting their maximum width at 1280, and then used the same steps to import those smaller files into PowerPoint. That worked: I was now looking at a Photo Album dialog listing 5,591 pictures. I clicked Create. PowerPoint seemed to freeze. An hour later, it hadn’t budged. I killed it and started over. This time, with those same photos, it crashed just a few minutes after I clicked Create. I tried again, this time using copies of the original photos that had been resized to 1280×720. The result: another crash. I tentatively concluded that PowerPoint was not going to be my first choice for producing a slideshow with so many slides.
To use office productivity software to produce a slideshow, it was perhaps not necessary to own or purchase Microsoft Office or PowerPoint. The same thing was at least theoretically feasible in the free LibreOffice Impress 5.2. With a new Impress presentation onscreen, as Wallen advised, I went to Insert > Media > Photo Album > Add > select JPGs > Open. I unchecked Add Caption to Each Slide and then clicked Insert Slides. After the customary 15-minute (?) delay, I saw that I had 5,592 slides, of which the first was a blank that I could develop for an introduction. It didn’t respond at first, and then I saw its Save Document progress indicator at the bottom of the screen. Apparently it was autosaving, so I had to wait for that.
On the menu, I saw a Slide Show option, but I didn’t want to have to start LibreOffice to play my slideshow. A search led to suggestions for PowerPoint to video converters (because Impress had the option of saving in PowerPoint PPT format) and also to the advice to use Impress > File > Export > Save as Type > Macromedia Flash (SWF), which could then be played directly or (if necessary) converted to another video format. I tried exporting to SWF with quality set to 100 (maximum). Unfortunately, this terminated with a message: “Fatal Error – bad allocation.” Oops — should have saved the slides in some form, because now Impress had crashed. I restarted Impress. It gave me a Document Recovery dialog. That failed with “General input/output error.” But then Document Recovery did look like it had saved it, after all — but then, when I tried to open the saved file, I got a message that it was corrupt. LibreOffice offered to repair it, but apparently that failed; LibreOffice disappeared.
Apparently I had buried Impress under too many JPGs. Another suggestion was to play the slideshow within LibreOffice, use screen capture, and edit that. There was also a suggestion to save in PPT format, and then install Microsoft’s PowerPoint Viewer to play the file. Of course, since I had PowerPoint, I could also use PowerPoint to open that file, created in Impress, and then export from PowerPoint. But all these possibilities depended on PowerPoint or LibreOffice being stable enough to handle so many JPGs, and that was not the reality. In short, for this particular project, PowerPoint and LibreOffice did not appear to be useful solutions.
ZIP and PDF Alternatives
For me, in this particular case, the primary advantage of the slideshow would be to display many files very quickly, without requiring me to sit there and keep tapping keys or clicking mouse buttons to move on to the next one. Between the EXE output of IrfanView and the video output of a dedicated slideshow program like PhotoStage, the latter would have the advantage because, at the time of slideshow assembly, or later in a video editing program, I could add captions, audio, and special effects. It also appeared more difficult to persuade IrfanView to preserve quality without preserving unnecessarily large file size.
As an alternative, if I wanted to preserve original image quality but didn’t want to have to sit or scan through a slideshow to find a particular image, then I might prefer to save files in a ZIP (i.e., compressed) file. This would be most useful if the files had good filenames, or were named and/or numbered in such a way that I could consult a separate file list or detailed index to find what I was looking for. I would probably not want to use the solid archiving option available in some ZIP programs (e.g., 7-Zip, WinRAR), since that would require the computer to unpack all of the files before it could show me the one I was looking for. Given that JPGs were already highly compressed, I would probably want to choose the Store option rather than actual compression. As noted in the other post, other options (e.g., recovery record) could affect the size of that ZIP file.
Another possibility was to combine the JPGs into a PDF file. In a PDF, it would be possible to change the order of pages (i.e., of photos). It would also be possible to add bookmarks (which might be automatically generated from filenames, provided they weren’t too long) and to arrange those bookmarks in subordinate groups within a hierarchical structure, so that a particular photo could be identified, not only by name, but also by topic. All of these things could be changed at any time, and images could be added or removed, with the use of a program like Adobe Acrobat. Indeed, finding junk images would be aided by Acrobat’s ability to display large thumbnails, permitting selection and deletion of multiple unwanted files. Acrobat would also permit any or all pages to be converted to other formats, including JPG.
I had noticed that my old version of Acrobat would import smaller numbers of files, but would crash when I tried importing too many. But this time, its option to Create PDF > Merge Files Into a Single PDF seemed to work. I designated the original 5,591 JPGs, designated the largest of the three compression icons displayed in Acrobat’s Combine Files dialog (signifying that I wanted minimal compression), and clicked the Combine Files button. That worked: after a relatively short delay, I wound up with a PDF — but it was only 848 pages long. Something had failed. A retry produced the same result. I didn’t think 848 was the limit — I was pretty sure I had created larger PDFs in the past — but 848 seemed to be the limit for this set, at least. In that case, I could take this process in several steps, combining 800 images at a time, and then combine the resulting PDFs. But I also noticed that the filesize was large, averaging about 1MB per JPG, for a prospective total of around 5.5GB for the whole set.
I had not previously tested the several quality options available in this version of Acrobat, but that average of 1MB per JPG would produce the 5.6GB total for the entire set of almost 5,600 original JPGs, suggesting little to no compression or loss of quality. A quick glance at a few slides supported that impression, at least to the point of full-screen viewing in Acrobat (i.e., 1920×1080). If I didn’t mind losing quality beyond that level (i.e., with images of higher resolution), perhaps I could reduce the size of the PDF by using IrfanView to produce JPG copies that would not be larger than 1920×1080 (not enlarging those that were already smaller than that, as indicated in the image of the IrfanView settings, above), and then create the PDF from those, again using Acrobat’s maximum quality setting. I remembered, at this point, the options available in Acrobat’s Edit > Preferences > Convert to PDF, but then I saw that, actually, there were no quality adjustments for JPGs (as distinct from e.g., BMPs or PNGs) there.
So I tried that. The set of 1920×1080 images produced by IrfanView took a total of 3.5GB of disk space. Acrobat combined them all into a single PDF of 5,591 pages. Unfortunately, at the final step, when I tried to name the resulting temp file named Binder2.pdf, I got an error: “The document could not be saved. This file is too big for the current operation.” Same thing on retry. I could not find Binder2.pdf on my drive; apparently it was a temporary file in memory. It was not a matter of drive space: there was plenty on the chosen drive, and attempting to save to a different drive did not help.
I tried Acrobat’s option of extracting and deleting pages from Binder2.pdf: extract pages 1 to 3000 and delete after extracting. That worked, partly: I was able to save the extracted pages as Part One.pdf, but I could still not save the remaining 2,591 pages as Part Two.pdf. I wondered whether Binder2.pdf itself was corrupted, so I created a new blank PDF and dragged all pages over from Binder2.pdf. But no, I still got the error. Back in Binder2.pdf, I repeated the extract-and-delete process, producing Part Two.pdf with 1,500 pages. Then I was able to save Part Three.pdf with the remaining 1,091 pages. The three files collectively took 3.7GB of disk space, which was actually a bit more than the original images. Spot checks suggested that image quality was similar to the 1920×1080 originals.
Unfortunately, my old version of Acrobat was still unwilling to combine and save those three PDFs in a single file. I got the same error message when I tried creating the file by selecting the JPGs in Windows Explorer > right-click > Combine supported files in Acrobat. Unlike the first approach, the temporary Binder1.pdf file created through this latter approach did include bookmarks, consisting of filenames, for each of the combined JPGs. (Acrobat’s search feature included an option to search bookmarks for the desired term.)
A Google search for the “too big” error message yielded indications that Acrobat could not save files larger than 2GB. I did not have any other PDFs larger than 2GB with which to test that claim. An attempt to combine and save other PDFs in a single 2.6GB file failed, so the claim tentatively appeared to be true. The only solutions I saw, in the results from that Google search, were to try Document > Optimize Scanned PDF or Document > Reduce File Size. The latter didn’t work because it started with a message (“The PDF document needs to be saved before it can be optimized”) and that saving attempt failed. I tried the Optimize Scanned PDF option, set to the smallest possible file size, with all improvement options (e.g., Deskew, Despeckle) turned off. That terminated with an error (“Scanned Image Optimization failed processing this page”).
So far, then, the best full-quality approach I had found was to use the right-click Acrobat PDF creation option (so as to generate bookmarks) on groups of files comprising less than 2GB each. But that would still leave me with several PDFs of less than 2GB each. There remained the possibility of choosing the smallest file size, so as to create a PDF that Acrobat could handle, with searchable bookmarks pointing toward the correct file. This PDF could be saved in conjunction with a ZIP file (used here as shorthand, to refer to any kind of compressed file, such as RAR or 7z) containing the original, full-quality JPGs. Then a search of the PDF could lead to the desired filename, which the user could verify by looking at its poor-quality PDF version; and, if desired, the user could then pull up the full-quality original from the separate ZIP file. A similar approach would use IrfanView to create resized thumbnail-like copies of the JPGs, which could be combined in full (albeit small) quality in Acrobat, again pointing toward that separate ZIP file or other archive. But I didn’t want a two-file solution.
PDFsam and Other PDF Alternatives
It seemed that, for this project, I would need a different PDF creator. A previous post named several Linux alternatives, some of which may have had Windows versions; AlternativeTo listed PDFsam (3.5 stars from 79 raters at Softpedia) as the most popular alternative to Acrobat across all operating systems; and Digital Trends listed four other nonfree programs (Foxit PhantomPDF, Nitro Pro, PDF Architect, and Nuance Power PDF) as less-expensive Acrobat alternatives for Windows.
I had previously used PDFsam (short for split-and-merge) for several different tasks, including some relatively complicated command-line jobs. I knew that not everybody would have Acrobat, and I wondered how PDFsam’s results would compare against Acrobat’s in this task. So I downloaded and installed PDFsam. The installer persuaded me to choose its Enhanced rather than Basic version. I was disappointed, along the way, to see that PDFsam was (newly?) affiliated with Soda PDF, with which I had previously had a minor bad experience. But I went ahead. In PDFsam, I clicked the View > Create PDF option. Using this involved registering with PDFsam in order to activate their Enhanced Create Module.
Once that was taken care of, I went to PDFsam > File > Create PDF > Combine Files > Add Folder. I designated the folder containing the 1920×1080 images. As with Acrobat, PDFsam now gave me an option of rearranging the PDFs — and also an option, potentially useful in conversions of EML (i.e., email) to PDF, to “Convert supported attachments of the combined files.” I clicked the Combine button at the top of the screen. PDFsam was a resource hog — the system slowed to a crawl while it was working — but within a timeframe similar to that of the other programs reviewed above, it did finish its work. Or nearly so: when it reached the 99% mark, it said, “Save document failed.” No explanation was offered, and a search for that term produced no results.
I wondered whether PDFsam would at least be able to combine the three files (Part One.pdf etc.) that Acrobat had produced (above). Taking the same steps as before, I had my answer: Yes! and it saved it. Acrobat was able to view that file. Surprisingly, Acrobat was also able to save a copy of that PDFsam-created file under a different filename. So it appeared that, for both Acrobat and PDFsam, the problem was not exactly with saving a file larger than 2GB, but rather with the complexity of saving a file created by converting so many large JPGs to PDF.
If I hadn’t had Acrobat, it seemed that I could have used PDFsam to create this large file in the same way: assemble several subsets of the whole set, and then combine those subsets into one file. At any rate, I did at last have a single PDF containing all 5,591 images. The size of the combined 5,591-page PDF that PDFsam had given me was 3.7GB. That seemed to indicate that PDFsam had not attempted to resize the three Part files produced by Acrobat. Spot checks seemed to indicate that image quality was still approximately the same as in the original JPGs.
Solution: A PDF Slideshow
I had previously used Acrobat’s less-than-maximum quality settings to save images. That was one approach. Sometimes I had been disappointed in the quality of the results. A search now led to suggestions regarding Acrobat’s settings for Page Display and conversion quality (above). These did not appear helpful in this case.
It seemed another approach would be to start with JPGs resized to no larger than the necessary resolution. I decided that, for what I would want from these images, 1280×720 (or perhaps I should have said 1280×1024) would be adequate. I wondered whether different photo resizing programs would produce different results. As detailed in another post, the short answer was: yes. That post compared resizing by IrfanView and FastStone, and concluded that, at least for these photos, with the right settings, I could squeeze the 5.6GB worth of original JPGs down into 1.6GB, with little to no loss of visible quality.
That solution might not have been right for other photos, but for what I needed from this particular set, those efforts positioned me to use the Acrobat right-click method (above) to combine all of these thousands of JPGs into a single PDF with good-quality images and bookmarks consisting of descriptive filenames. The PDF approach would give me the option of searching bookmarks for particular terms, rearranging and renaming bookmarks and images, deleting unwanted images, and extracting images into a variety of formats (e.g., JPG) as desired.
The missing piece, in the PDF approach, was that I would have to use arrow keys or mouse clicks to move through the images manually, instead of sitting back and watching a slideshow. But — not! As it turned out, there was a way to view the pages of a PDF as a slideshow. Creative Techs and Gordon offered these steps, which appeared to be nearly identical for Acrobat and for Adobe Reader: Edit > Preferences > Full Screen > click Advance Every ___ seconds. (When I attempted 0.3 seconds, I got a message: “The value must be between 1 and 60.” So that would be one drawback of this approach.) Optionally, in that same screen, I could also click Loop after last page. With the PDF onscreen, I could also select View > Full Screen Mode and File > Properties > Open in Full Screen Mode.
Those steps worked for my 5,591-page PDF. I had a slideshow along with the other benefits of the PDF format. If I really wanted a faster slideshow, I could do a screen capture (my tool: Debut) and then use Media Player Classic > Ctrl-UpArrow (repeatedly) to play it at some multiple of the original.